{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1998
Type and Coercion - friends' interface
-}

{-# LANGUAGE CPP #-}
{-# LANGUAGE BangPatterns #-}

-- | Substitution into types and coercions.
module TyCoSubst
  (
        -- * Substitutions
        TCvSubst(..), TvSubstEnv, CvSubstEnv,
        emptyTvSubstEnv, emptyCvSubstEnv, composeTCvSubstEnv, composeTCvSubst,
        emptyTCvSubst, mkEmptyTCvSubst, isEmptyTCvSubst,
        mkTCvSubst, mkTvSubst, mkCvSubst,
        getTvSubstEnv,
        getCvSubstEnv, getTCvInScope, getTCvSubstRangeFVs,
        isInScope, notElemTCvSubst,
        setTvSubstEnv, setCvSubstEnv, zapTCvSubst,
        extendTCvInScope, extendTCvInScopeList, extendTCvInScopeSet,
        extendTCvSubst, extendTCvSubstWithClone,
        extendCvSubst, extendCvSubstWithClone,
        extendTvSubst, extendTvSubstBinderAndInScope, extendTvSubstWithClone,
        extendTvSubstList, extendTvSubstAndInScope,
        extendTCvSubstList,
        unionTCvSubst, zipTyEnv, zipCoEnv, mkTyCoInScopeSet,
        zipTvSubst, zipCvSubst,
        zipTCvSubst,
        mkTvSubstPrs,

        substTyWith, substTyWithCoVars, substTysWith, substTysWithCoVars,
        substCoWith,
        substTy, substTyAddInScope,
        substTyUnchecked, substTysUnchecked, substThetaUnchecked,
        substTyWithUnchecked,
        substCoUnchecked, substCoWithUnchecked,
        substTyWithInScope,
        substTys, substTheta,
        lookupTyVar,
        substCo, substCos, substCoVar, substCoVars, lookupCoVar,
        cloneTyVarBndr, cloneTyVarBndrs,
        substVarBndr, substVarBndrs,
        substTyVarBndr, substTyVarBndrs,
        substCoVarBndr,
        substTyVar, substTyVars, substTyCoVars,
        substForAllCoBndr,
        substVarBndrUsing, substForAllCoBndrUsing,
        checkValidSubst, isValidTCvSubst,
  ) where

#include "HsVersions.h"

import GhcPrelude

import {-# SOURCE #-} Type ( mkCastTy, mkAppTy, isCoercionTy )
import {-# SOURCE #-} Coercion ( mkCoVarCo, mkKindCo, mkNthCo, mkTransCo
                               , mkNomReflCo, mkSubCo, mkSymCo
                               , mkFunCo, mkForAllCo, mkUnivCo
                               , mkAxiomInstCo, mkAppCo, mkGReflCo
                               , mkInstCo, mkLRCo, mkTyConAppCo
                               , mkCoercionType
                               , coercionKind, coVarKindsTypesRole )

import TyCoRep
import TyCoFVs
import TyCoPpr

import Var
import VarSet
import VarEnv

import Pair
import Util
import UniqSupply
import Unique
import UniqFM
import UniqSet
import Outputable

import Data.List (mapAccumL)

{-
%************************************************************************
%*                                                                      *
                        Substitutions
      Data type defined here to avoid unnecessary mutual recursion
%*                                                                      *
%************************************************************************
-}

-- | Type & coercion substitution
--
-- #tcvsubst_invariant#
-- The following invariants must hold of a 'TCvSubst':
--
-- 1. The in-scope set is needed /only/ to
-- guide the generation of fresh uniques
--
-- 2. In particular, the /kind/ of the type variables in
-- the in-scope set is not relevant
--
-- 3. The substitution is only applied ONCE! This is because
-- in general such application will not reach a fixed point.
data TCvSubst
  = TCvSubst InScopeSet -- The in-scope type and kind variables
             TvSubstEnv -- Substitutes both type and kind variables
             CvSubstEnv -- Substitutes coercion variables
        -- See Note [Substitutions apply only once]
        -- and Note [Extending the TvSubstEnv]
        -- and Note [Substituting types and coercions]
        -- and Note [The substitution invariant]

-- | A substitution of 'Type's for 'TyVar's
--                 and 'Kind's for 'KindVar's
type TvSubstEnv = TyVarEnv Type
  -- NB: A TvSubstEnv is used
  --   both inside a TCvSubst (with the apply-once invariant
  --        discussed in Note [Substitutions apply only once],
  --   and  also independently in the middle of matching,
  --        and unification (see Types.Unify).
  -- So you have to look at the context to know if it's idempotent or
  -- apply-once or whatever

-- | A substitution of 'Coercion's for 'CoVar's
type CvSubstEnv = CoVarEnv Coercion

{- Note [The substitution invariant]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When calling (substTy subst ty) it should be the case that
the in-scope set in the substitution is a superset of both:

  (SIa) The free vars of the range of the substitution
  (SIb) The free vars of ty minus the domain of the substitution

The same rules apply to other substitutions (notably CoreSubst.Subst)

* Reason for (SIa). Consider
      substTy [a :-> Maybe b] (forall b. b->a)
  we must rename the forall b, to get
      forall b2. b2 -> Maybe b
  Making 'b' part of the in-scope set forces this renaming to
  take place.

* Reason for (SIb). Consider
     substTy [a :-> Maybe b] (forall b. (a,b,x))
  Then if we use the in-scope set {b}, satisfying (SIa), there is
  a danger we will rename the forall'd variable to 'x' by mistake,
  getting this:
      forall x. (Maybe b, x, x)
  Breaking (SIb) caused the bug from #11371.

Note: if the free vars of the range of the substitution are freshly created,
then the problems of (SIa) can't happen, and so it would be sound to
ignore (SIa).

Note [Substitutions apply only once]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We use TCvSubsts to instantiate things, and we might instantiate
        forall a b. ty
with the types
        [a, b], or [b, a].
So the substitution might go [a->b, b->a].  A similar situation arises in Core
when we find a beta redex like
        (/\ a /\ b -> e) b a
Then we also end up with a substitution that permutes type variables. Other
variations happen to; for example [a -> (a, b)].

        ********************************************************
        *** So a substitution must be applied precisely once ***
        ********************************************************

A TCvSubst is not idempotent, but, unlike the non-idempotent substitution
we use during unifications, it must not be repeatedly applied.

Note [Extending the TvSubstEnv]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
See #tcvsubst_invariant# for the invariants that must hold.

This invariant allows a short-cut when the subst envs are empty:
if the TvSubstEnv and CvSubstEnv are empty --- i.e. (isEmptyTCvSubst subst)
holds --- then (substTy subst ty) does nothing.

For example, consider:
        (/\a. /\b:(a~Int). ...b..) Int
We substitute Int for 'a'.  The Unique of 'b' does not change, but
nevertheless we add 'b' to the TvSubstEnv, because b's kind does change

This invariant has several crucial consequences:

* In substVarBndr, we need extend the TvSubstEnv
        - if the unique has changed
        - or if the kind has changed

* In substTyVar, we do not need to consult the in-scope set;
  the TvSubstEnv is enough

* In substTy, substTheta, we can short-circuit when the TvSubstEnv is empty

Note [Substituting types and coercions]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Types and coercions are mutually recursive, and either may have variables
"belonging" to the other. Thus, every time we wish to substitute in a
type, we may also need to substitute in a coercion, and vice versa.
However, the constructor used to create type variables is distinct from
that of coercion variables, so we carry two VarEnvs in a TCvSubst. Note
that it would be possible to use the CoercionTy constructor to combine
these environments, but that seems like a false economy.

Note that the TvSubstEnv should *never* map a CoVar (built with the Id
constructor) and the CvSubstEnv should *never* map a TyVar. Furthermore,
the range of the TvSubstEnv should *never* include a type headed with
CoercionTy.
-}

emptyTvSubstEnv :: TvSubstEnv
emptyTvSubstEnv :: TvSubstEnv
emptyTvSubstEnv = TvSubstEnv
forall a. VarEnv a
emptyVarEnv

emptyCvSubstEnv :: CvSubstEnv
emptyCvSubstEnv :: CvSubstEnv
emptyCvSubstEnv = CvSubstEnv
forall a. VarEnv a
emptyVarEnv

composeTCvSubstEnv :: InScopeSet
                   -> (TvSubstEnv, CvSubstEnv)
                   -> (TvSubstEnv, CvSubstEnv)
                   -> (TvSubstEnv, CvSubstEnv)
-- ^ @(compose env1 env2)(x)@ is @env1(env2(x))@; i.e. apply @env2@ then @env1@.
-- It assumes that both are idempotent.
-- Typically, @env1@ is the refinement to a base substitution @env2@
composeTCvSubstEnv :: InScopeSet
-> (TvSubstEnv, CvSubstEnv)
-> (TvSubstEnv, CvSubstEnv)
-> (TvSubstEnv, CvSubstEnv)
composeTCvSubstEnv InScopeSet
in_scope (TvSubstEnv
tenv1, CvSubstEnv
cenv1) (TvSubstEnv
tenv2, CvSubstEnv
cenv2)
  = ( TvSubstEnv
tenv1 TvSubstEnv -> TvSubstEnv -> TvSubstEnv
forall a. VarEnv a -> VarEnv a -> VarEnv a
`plusVarEnv` (Type -> Type) -> TvSubstEnv -> TvSubstEnv
forall a b. (a -> b) -> VarEnv a -> VarEnv b
mapVarEnv (HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy TCvSubst
subst1) TvSubstEnv
tenv2
    , CvSubstEnv
cenv1 CvSubstEnv -> CvSubstEnv -> CvSubstEnv
forall a. VarEnv a -> VarEnv a -> VarEnv a
`plusVarEnv` (Coercion -> Coercion) -> CvSubstEnv -> CvSubstEnv
forall a b. (a -> b) -> VarEnv a -> VarEnv b
mapVarEnv (HasCallStack => TCvSubst -> Coercion -> Coercion
TCvSubst -> Coercion -> Coercion
substCo TCvSubst
subst1) CvSubstEnv
cenv2 )
        -- First apply env1 to the range of env2
        -- Then combine the two, making sure that env1 loses if
        -- both bind the same variable; that's why env1 is the
        --  *left* argument to plusVarEnv, because the right arg wins
  where
    subst1 :: TCvSubst
subst1 = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
tenv1 CvSubstEnv
cenv1

-- | Composes two substitutions, applying the second one provided first,
-- like in function composition.
composeTCvSubst :: TCvSubst -> TCvSubst -> TCvSubst
composeTCvSubst :: TCvSubst -> TCvSubst -> TCvSubst
composeTCvSubst (TCvSubst InScopeSet
is1 TvSubstEnv
tenv1 CvSubstEnv
cenv1) (TCvSubst InScopeSet
is2 TvSubstEnv
tenv2 CvSubstEnv
cenv2)
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
is3 TvSubstEnv
tenv3 CvSubstEnv
cenv3
  where
    is3 :: InScopeSet
is3 = InScopeSet
is1 InScopeSet -> InScopeSet -> InScopeSet
`unionInScope` InScopeSet
is2
    (TvSubstEnv
tenv3, CvSubstEnv
cenv3) = InScopeSet
-> (TvSubstEnv, CvSubstEnv)
-> (TvSubstEnv, CvSubstEnv)
-> (TvSubstEnv, CvSubstEnv)
composeTCvSubstEnv InScopeSet
is3 (TvSubstEnv
tenv1, CvSubstEnv
cenv1) (TvSubstEnv
tenv2, CvSubstEnv
cenv2)

emptyTCvSubst :: TCvSubst
emptyTCvSubst :: TCvSubst
emptyTCvSubst = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
emptyInScopeSet TvSubstEnv
emptyTvSubstEnv CvSubstEnv
emptyCvSubstEnv

mkEmptyTCvSubst :: InScopeSet -> TCvSubst
mkEmptyTCvSubst :: InScopeSet -> TCvSubst
mkEmptyTCvSubst InScopeSet
is = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
is TvSubstEnv
emptyTvSubstEnv CvSubstEnv
emptyCvSubstEnv

isEmptyTCvSubst :: TCvSubst -> Bool
         -- See Note [Extending the TvSubstEnv]
isEmptyTCvSubst :: TCvSubst -> Bool
isEmptyTCvSubst (TCvSubst InScopeSet
_ TvSubstEnv
tenv CvSubstEnv
cenv) = TvSubstEnv -> Bool
forall a. VarEnv a -> Bool
isEmptyVarEnv TvSubstEnv
tenv Bool -> Bool -> Bool
&& CvSubstEnv -> Bool
forall a. VarEnv a -> Bool
isEmptyVarEnv CvSubstEnv
cenv

mkTCvSubst :: InScopeSet -> (TvSubstEnv, CvSubstEnv) -> TCvSubst
mkTCvSubst :: InScopeSet -> (TvSubstEnv, CvSubstEnv) -> TCvSubst
mkTCvSubst InScopeSet
in_scope (TvSubstEnv
tenv, CvSubstEnv
cenv) = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv

mkTvSubst :: InScopeSet -> TvSubstEnv -> TCvSubst
-- ^ Make a TCvSubst with specified tyvar subst and empty covar subst
mkTvSubst :: InScopeSet -> TvSubstEnv -> TCvSubst
mkTvSubst InScopeSet
in_scope TvSubstEnv
tenv = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
emptyCvSubstEnv

mkCvSubst :: InScopeSet -> CvSubstEnv -> TCvSubst
-- ^ Make a TCvSubst with specified covar subst and empty tyvar subst
mkCvSubst :: InScopeSet -> CvSubstEnv -> TCvSubst
mkCvSubst InScopeSet
in_scope CvSubstEnv
cenv = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
emptyTvSubstEnv CvSubstEnv
cenv

getTvSubstEnv :: TCvSubst -> TvSubstEnv
getTvSubstEnv :: TCvSubst -> TvSubstEnv
getTvSubstEnv (TCvSubst InScopeSet
_ TvSubstEnv
env CvSubstEnv
_) = TvSubstEnv
env

getCvSubstEnv :: TCvSubst -> CvSubstEnv
getCvSubstEnv :: TCvSubst -> CvSubstEnv
getCvSubstEnv (TCvSubst InScopeSet
_ TvSubstEnv
_ CvSubstEnv
env) = CvSubstEnv
env

getTCvInScope :: TCvSubst -> InScopeSet
getTCvInScope :: TCvSubst -> InScopeSet
getTCvInScope (TCvSubst InScopeSet
in_scope TvSubstEnv
_ CvSubstEnv
_) = InScopeSet
in_scope

-- | Returns the free variables of the types in the range of a substitution as
-- a non-deterministic set.
getTCvSubstRangeFVs :: TCvSubst -> VarSet
getTCvSubstRangeFVs :: TCvSubst -> VarSet
getTCvSubstRangeFVs (TCvSubst InScopeSet
_ TvSubstEnv
tenv CvSubstEnv
cenv)
    = VarSet -> VarSet -> VarSet
unionVarSet VarSet
tenvFVs VarSet
cenvFVs
  where
    tenvFVs :: VarSet
tenvFVs = TvSubstEnv -> VarSet
tyCoVarsOfTypesSet TvSubstEnv
tenv
    cenvFVs :: VarSet
cenvFVs = CvSubstEnv -> VarSet
tyCoVarsOfCosSet CvSubstEnv
cenv

isInScope :: Var -> TCvSubst -> Bool
isInScope :: Var -> TCvSubst -> Bool
isInScope Var
v (TCvSubst InScopeSet
in_scope TvSubstEnv
_ CvSubstEnv
_) = Var
v Var -> InScopeSet -> Bool
`elemInScopeSet` InScopeSet
in_scope

notElemTCvSubst :: Var -> TCvSubst -> Bool
notElemTCvSubst :: Var -> TCvSubst -> Bool
notElemTCvSubst Var
v (TCvSubst InScopeSet
_ TvSubstEnv
tenv CvSubstEnv
cenv)
  | Var -> Bool
isTyVar Var
v
  = Bool -> Bool
not (Var
v Var -> TvSubstEnv -> Bool
forall a. Var -> VarEnv a -> Bool
`elemVarEnv` TvSubstEnv
tenv)
  | Bool
otherwise
  = Bool -> Bool
not (Var
v Var -> CvSubstEnv -> Bool
forall a. Var -> VarEnv a -> Bool
`elemVarEnv` CvSubstEnv
cenv)

setTvSubstEnv :: TCvSubst -> TvSubstEnv -> TCvSubst
setTvSubstEnv :: TCvSubst -> TvSubstEnv -> TCvSubst
setTvSubstEnv (TCvSubst InScopeSet
in_scope TvSubstEnv
_ CvSubstEnv
cenv) TvSubstEnv
tenv = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv

setCvSubstEnv :: TCvSubst -> CvSubstEnv -> TCvSubst
setCvSubstEnv :: TCvSubst -> CvSubstEnv -> TCvSubst
setCvSubstEnv (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
_) CvSubstEnv
cenv = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv

zapTCvSubst :: TCvSubst -> TCvSubst
zapTCvSubst :: TCvSubst -> TCvSubst
zapTCvSubst (TCvSubst InScopeSet
in_scope TvSubstEnv
_ CvSubstEnv
_) = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
forall a. VarEnv a
emptyVarEnv CvSubstEnv
forall a. VarEnv a
emptyVarEnv

extendTCvInScope :: TCvSubst -> Var -> TCvSubst
extendTCvInScope :: TCvSubst -> Var -> TCvSubst
extendTCvInScope (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
var
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet -> Var -> InScopeSet
extendInScopeSet InScopeSet
in_scope Var
var) TvSubstEnv
tenv CvSubstEnv
cenv

extendTCvInScopeList :: TCvSubst -> [Var] -> TCvSubst
extendTCvInScopeList :: TCvSubst -> [Var] -> TCvSubst
extendTCvInScopeList (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) [Var]
vars
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet -> [Var] -> InScopeSet
extendInScopeSetList InScopeSet
in_scope [Var]
vars) TvSubstEnv
tenv CvSubstEnv
cenv

extendTCvInScopeSet :: TCvSubst -> VarSet -> TCvSubst
extendTCvInScopeSet :: TCvSubst -> VarSet -> TCvSubst
extendTCvInScopeSet (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) VarSet
vars
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet -> VarSet -> InScopeSet
extendInScopeSetSet InScopeSet
in_scope VarSet
vars) TvSubstEnv
tenv CvSubstEnv
cenv

extendTCvSubst :: TCvSubst -> TyCoVar -> Type -> TCvSubst
extendTCvSubst :: TCvSubst -> Var -> Type -> TCvSubst
extendTCvSubst TCvSubst
subst Var
v Type
ty
  | Var -> Bool
isTyVar Var
v
  = TCvSubst -> Var -> Type -> TCvSubst
extendTvSubst TCvSubst
subst Var
v Type
ty
  | CoercionTy Coercion
co <- Type
ty
  = TCvSubst -> Var -> Coercion -> TCvSubst
extendCvSubst TCvSubst
subst Var
v Coercion
co
  | Bool
otherwise
  = String -> SDoc -> TCvSubst
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"extendTCvSubst" (Var -> SDoc
forall a. Outputable a => a -> SDoc
ppr Var
v SDoc -> SDoc -> SDoc
<+> String -> SDoc
text String
"|->" SDoc -> SDoc -> SDoc
<+> Type -> SDoc
forall a. Outputable a => a -> SDoc
ppr Type
ty)

extendTCvSubstWithClone :: TCvSubst -> TyCoVar -> TyCoVar -> TCvSubst
extendTCvSubstWithClone :: TCvSubst -> Var -> Var -> TCvSubst
extendTCvSubstWithClone TCvSubst
subst Var
tcv
  | Var -> Bool
isTyVar Var
tcv = TCvSubst -> Var -> Var -> TCvSubst
extendTvSubstWithClone TCvSubst
subst Var
tcv
  | Bool
otherwise   = TCvSubst -> Var -> Var -> TCvSubst
extendCvSubstWithClone TCvSubst
subst Var
tcv

extendTvSubst :: TCvSubst -> TyVar -> Type -> TCvSubst
extendTvSubst :: TCvSubst -> Var -> Type -> TCvSubst
extendTvSubst (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
tv Type
ty
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope (TvSubstEnv -> Var -> Type -> TvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv TvSubstEnv
tenv Var
tv Type
ty) CvSubstEnv
cenv

extendTvSubstBinderAndInScope :: TCvSubst -> TyCoBinder -> Type -> TCvSubst
extendTvSubstBinderAndInScope :: TCvSubst -> TyCoBinder -> Type -> TCvSubst
extendTvSubstBinderAndInScope TCvSubst
subst (Named (Bndr Var
v ArgFlag
_)) Type
ty
  = ASSERT( isTyVar v )
    TCvSubst -> Var -> Type -> TCvSubst
extendTvSubstAndInScope TCvSubst
subst Var
v Type
ty
extendTvSubstBinderAndInScope TCvSubst
subst (Anon {}) Type
_
  = TCvSubst
subst

extendTvSubstWithClone :: TCvSubst -> TyVar -> TyVar -> TCvSubst
-- Adds a new tv -> tv mapping, /and/ extends the in-scope set
extendTvSubstWithClone :: TCvSubst -> Var -> Var -> TCvSubst
extendTvSubstWithClone (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
tv Var
tv'
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet -> VarSet -> InScopeSet
extendInScopeSetSet InScopeSet
in_scope VarSet
new_in_scope)
             (TvSubstEnv -> Var -> Type -> TvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv TvSubstEnv
tenv Var
tv (Var -> Type
mkTyVarTy Var
tv'))
             CvSubstEnv
cenv
  where
    new_in_scope :: VarSet
new_in_scope = Type -> VarSet
tyCoVarsOfType (Var -> Type
tyVarKind Var
tv') VarSet -> Var -> VarSet
`extendVarSet` Var
tv'

extendCvSubst :: TCvSubst -> CoVar -> Coercion -> TCvSubst
extendCvSubst :: TCvSubst -> Var -> Coercion -> TCvSubst
extendCvSubst (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
v Coercion
co
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst InScopeSet
in_scope TvSubstEnv
tenv (CvSubstEnv -> Var -> Coercion -> CvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv CvSubstEnv
cenv Var
v Coercion
co)

extendCvSubstWithClone :: TCvSubst -> CoVar -> CoVar -> TCvSubst
extendCvSubstWithClone :: TCvSubst -> Var -> Var -> TCvSubst
extendCvSubstWithClone (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
cv Var
cv'
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet -> VarSet -> InScopeSet
extendInScopeSetSet InScopeSet
in_scope VarSet
new_in_scope)
             TvSubstEnv
tenv
             (CvSubstEnv -> Var -> Coercion -> CvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv CvSubstEnv
cenv Var
cv (Var -> Coercion
mkCoVarCo Var
cv'))
  where
    new_in_scope :: VarSet
new_in_scope = Type -> VarSet
tyCoVarsOfType (Var -> Type
varType Var
cv') VarSet -> Var -> VarSet
`extendVarSet` Var
cv'

extendTvSubstAndInScope :: TCvSubst -> TyVar -> Type -> TCvSubst
-- Also extends the in-scope set
extendTvSubstAndInScope :: TCvSubst -> Var -> Type -> TCvSubst
extendTvSubstAndInScope (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
tv Type
ty
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet
in_scope InScopeSet -> VarSet -> InScopeSet
`extendInScopeSetSet` Type -> VarSet
tyCoVarsOfType Type
ty)
             (TvSubstEnv -> Var -> Type -> TvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv TvSubstEnv
tenv Var
tv Type
ty)
             CvSubstEnv
cenv

extendTvSubstList :: TCvSubst -> [Var] -> [Type] -> TCvSubst
extendTvSubstList :: TCvSubst -> [Var] -> [Type] -> TCvSubst
extendTvSubstList TCvSubst
subst [Var]
tvs [Type]
tys
  = (TCvSubst -> Var -> Type -> TCvSubst)
-> TCvSubst -> [Var] -> [Type] -> TCvSubst
forall acc a b. (acc -> a -> b -> acc) -> acc -> [a] -> [b] -> acc
foldl2 TCvSubst -> Var -> Type -> TCvSubst
extendTvSubst TCvSubst
subst [Var]
tvs [Type]
tys

extendTCvSubstList :: TCvSubst -> [Var] -> [Type] -> TCvSubst
extendTCvSubstList :: TCvSubst -> [Var] -> [Type] -> TCvSubst
extendTCvSubstList TCvSubst
subst [Var]
tvs [Type]
tys
  = (TCvSubst -> Var -> Type -> TCvSubst)
-> TCvSubst -> [Var] -> [Type] -> TCvSubst
forall acc a b. (acc -> a -> b -> acc) -> acc -> [a] -> [b] -> acc
foldl2 TCvSubst -> Var -> Type -> TCvSubst
extendTCvSubst TCvSubst
subst [Var]
tvs [Type]
tys

unionTCvSubst :: TCvSubst -> TCvSubst -> TCvSubst
-- Works when the ranges are disjoint
unionTCvSubst :: TCvSubst -> TCvSubst -> TCvSubst
unionTCvSubst (TCvSubst InScopeSet
in_scope1 TvSubstEnv
tenv1 CvSubstEnv
cenv1) (TCvSubst InScopeSet
in_scope2 TvSubstEnv
tenv2 CvSubstEnv
cenv2)
  = ASSERT( not (tenv1 `intersectsVarEnv` tenv2)
         && not (cenv1 `intersectsVarEnv` cenv2) )
    InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet
in_scope1 InScopeSet -> InScopeSet -> InScopeSet
`unionInScope` InScopeSet
in_scope2)
             (TvSubstEnv
tenv1     TvSubstEnv -> TvSubstEnv -> TvSubstEnv
forall a. VarEnv a -> VarEnv a -> VarEnv a
`plusVarEnv`   TvSubstEnv
tenv2)
             (CvSubstEnv
cenv1     CvSubstEnv -> CvSubstEnv -> CvSubstEnv
forall a. VarEnv a -> VarEnv a -> VarEnv a
`plusVarEnv`   CvSubstEnv
cenv2)

-- mkTvSubstPrs and zipTvSubst generate the in-scope set from
-- the types given; but it's just a thunk so with a bit of luck
-- it'll never be evaluated

-- | Generates the in-scope set for the 'TCvSubst' from the types in the incoming
-- environment. No CoVars, please!
zipTvSubst :: HasDebugCallStack => [TyVar] -> [Type] -> TCvSubst
zipTvSubst :: [Var] -> [Type] -> TCvSubst
zipTvSubst [Var]
tvs [Type]
tys
  = InScopeSet -> TvSubstEnv -> TCvSubst
mkTvSubst (VarSet -> InScopeSet
mkInScopeSet ([Type] -> VarSet
tyCoVarsOfTypes [Type]
tys)) TvSubstEnv
tenv
  where
    tenv :: TvSubstEnv
tenv = [Var] -> [Type] -> TvSubstEnv
HasDebugCallStack => [Var] -> [Type] -> TvSubstEnv
zipTyEnv [Var]
tvs [Type]
tys

-- | Generates the in-scope set for the 'TCvSubst' from the types in the incoming
-- environment.  No TyVars, please!
zipCvSubst :: HasDebugCallStack => [CoVar] -> [Coercion] -> TCvSubst
zipCvSubst :: [Var] -> [Coercion] -> TCvSubst
zipCvSubst [Var]
cvs [Coercion]
cos
  = InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (VarSet -> InScopeSet
mkInScopeSet ([Coercion] -> VarSet
tyCoVarsOfCos [Coercion]
cos)) TvSubstEnv
emptyTvSubstEnv CvSubstEnv
cenv
  where
    cenv :: CvSubstEnv
cenv = [Var] -> [Coercion] -> CvSubstEnv
HasDebugCallStack => [Var] -> [Coercion] -> CvSubstEnv
zipCoEnv [Var]
cvs [Coercion]
cos

zipTCvSubst :: HasDebugCallStack => [TyCoVar] -> [Type] -> TCvSubst
zipTCvSubst :: [Var] -> [Type] -> TCvSubst
zipTCvSubst [Var]
tcvs [Type]
tys
  = [Var] -> [Type] -> TCvSubst -> TCvSubst
zip_tcvsubst [Var]
tcvs [Type]
tys (InScopeSet -> TCvSubst
mkEmptyTCvSubst (InScopeSet -> TCvSubst) -> InScopeSet -> TCvSubst
forall a b. (a -> b) -> a -> b
$ VarSet -> InScopeSet
mkInScopeSet ([Type] -> VarSet
tyCoVarsOfTypes [Type]
tys))
  where zip_tcvsubst :: [TyCoVar] -> [Type] -> TCvSubst -> TCvSubst
        zip_tcvsubst :: [Var] -> [Type] -> TCvSubst -> TCvSubst
zip_tcvsubst (Var
tv:[Var]
tvs) (Type
ty:[Type]
tys) TCvSubst
subst
          = [Var] -> [Type] -> TCvSubst -> TCvSubst
zip_tcvsubst [Var]
tvs [Type]
tys (TCvSubst -> Var -> Type -> TCvSubst
extendTCvSubst TCvSubst
subst Var
tv Type
ty)
        zip_tcvsubst [] [] TCvSubst
subst = TCvSubst
subst -- empty case
        zip_tcvsubst [Var]
_  [Type]
_  TCvSubst
_     = String -> SDoc -> TCvSubst
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"zipTCvSubst: length mismatch"
                                            ([Var] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Var]
tcvs SDoc -> SDoc -> SDoc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
tys)

-- | Generates the in-scope set for the 'TCvSubst' from the types in the
-- incoming environment. No CoVars, please!
mkTvSubstPrs :: [(TyVar, Type)] -> TCvSubst
mkTvSubstPrs :: [(Var, Type)] -> TCvSubst
mkTvSubstPrs [(Var, Type)]
prs =
    ASSERT2( onlyTyVarsAndNoCoercionTy, text "prs" <+> ppr prs )
    InScopeSet -> TvSubstEnv -> TCvSubst
mkTvSubst InScopeSet
in_scope TvSubstEnv
tenv
  where tenv :: TvSubstEnv
tenv = [(Var, Type)] -> TvSubstEnv
forall a. [(Var, a)] -> VarEnv a
mkVarEnv [(Var, Type)]
prs
        in_scope :: InScopeSet
in_scope = VarSet -> InScopeSet
mkInScopeSet (VarSet -> InScopeSet) -> VarSet -> InScopeSet
forall a b. (a -> b) -> a -> b
$ [Type] -> VarSet
tyCoVarsOfTypes ([Type] -> VarSet) -> [Type] -> VarSet
forall a b. (a -> b) -> a -> b
$ ((Var, Type) -> Type) -> [(Var, Type)] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map (Var, Type) -> Type
forall a b. (a, b) -> b
snd [(Var, Type)]
prs
        onlyTyVarsAndNoCoercionTy :: Bool
onlyTyVarsAndNoCoercionTy =
          [Bool] -> Bool
forall (t :: * -> *). Foldable t => t Bool -> Bool
and [ Var -> Bool
isTyVar Var
tv Bool -> Bool -> Bool
&& Bool -> Bool
not (Type -> Bool
isCoercionTy Type
ty)
              | (Var
tv, Type
ty) <- [(Var, Type)]
prs ]

zipTyEnv :: HasDebugCallStack => [TyVar] -> [Type] -> TvSubstEnv
zipTyEnv :: [Var] -> [Type] -> TvSubstEnv
zipTyEnv [Var]
tyvars [Type]
tys
  | Bool
debugIsOn
  , Bool -> Bool
not ((Var -> Bool) -> [Var] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all Var -> Bool
isTyVar [Var]
tyvars)
  = String -> SDoc -> TvSubstEnv
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"zipTyEnv" ([Var] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Var]
tyvars SDoc -> SDoc -> SDoc
<+> [Type] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Type]
tys)
  | Bool
otherwise
  = ASSERT( all (not . isCoercionTy) tys )
    [(Var, Type)] -> TvSubstEnv
forall a. [(Var, a)] -> VarEnv a
mkVarEnv (String -> [Var] -> [Type] -> [(Var, Type)]
forall a b. String -> [a] -> [b] -> [(a, b)]
zipEqual String
"zipTyEnv" [Var]
tyvars [Type]
tys)
        -- There used to be a special case for when
        --      ty == TyVarTy tv
        -- (a not-uncommon case) in which case the substitution was dropped.
        -- But the type-tidier changes the print-name of a type variable without
        -- changing the unique, and that led to a bug.   Why?  Pre-tidying, we had
        -- a type {Foo t}, where Foo is a one-method class.  So Foo is really a newtype.
        -- And it happened that t was the type variable of the class.  Post-tiding,
        -- it got turned into {Foo t2}.  The ext-core printer expanded this using
        -- sourceTypeRep, but that said "Oh, t == t2" because they have the same unique,
        -- and so generated a rep type mentioning t not t2.
        --
        -- Simplest fix is to nuke the "optimisation"

zipCoEnv :: HasDebugCallStack => [CoVar] -> [Coercion] -> CvSubstEnv
zipCoEnv :: [Var] -> [Coercion] -> CvSubstEnv
zipCoEnv [Var]
cvs [Coercion]
cos
  | Bool
debugIsOn
  , Bool -> Bool
not ((Var -> Bool) -> [Var] -> Bool
forall (t :: * -> *) a. Foldable t => (a -> Bool) -> t a -> Bool
all Var -> Bool
isCoVar [Var]
cvs)
  = String -> SDoc -> CvSubstEnv
forall a. HasCallStack => String -> SDoc -> a
pprPanic String
"zipCoEnv" ([Var] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Var]
cvs SDoc -> SDoc -> SDoc
<+> [Coercion] -> SDoc
forall a. Outputable a => a -> SDoc
ppr [Coercion]
cos)
  | Bool
otherwise
  = [(Var, Coercion)] -> CvSubstEnv
forall a. [(Var, a)] -> VarEnv a
mkVarEnv (String -> [Var] -> [Coercion] -> [(Var, Coercion)]
forall a b. String -> [a] -> [b] -> [(a, b)]
zipEqual String
"zipCoEnv" [Var]
cvs [Coercion]
cos)

instance Outputable TCvSubst where
  ppr :: TCvSubst -> SDoc
ppr (TCvSubst InScopeSet
ins TvSubstEnv
tenv CvSubstEnv
cenv)
    = SDoc -> SDoc
brackets (SDoc -> SDoc) -> SDoc -> SDoc
forall a b. (a -> b) -> a -> b
$ [SDoc] -> SDoc
sep[ String -> SDoc
text String
"TCvSubst",
                      Int -> SDoc -> SDoc
nest Int
2 (String -> SDoc
text String
"In scope:" SDoc -> SDoc -> SDoc
<+> InScopeSet -> SDoc
forall a. Outputable a => a -> SDoc
ppr InScopeSet
ins),
                      Int -> SDoc -> SDoc
nest Int
2 (String -> SDoc
text String
"Type env:" SDoc -> SDoc -> SDoc
<+> TvSubstEnv -> SDoc
forall a. Outputable a => a -> SDoc
ppr TvSubstEnv
tenv),
                      Int -> SDoc -> SDoc
nest Int
2 (String -> SDoc
text String
"Co env:" SDoc -> SDoc -> SDoc
<+> CvSubstEnv -> SDoc
forall a. Outputable a => a -> SDoc
ppr CvSubstEnv
cenv) ]

{-
%************************************************************************
%*                                                                      *
                Performing type or kind substitutions
%*                                                                      *
%************************************************************************

Note [Sym and ForAllCo]
~~~~~~~~~~~~~~~~~~~~~~~
In OptCoercion, we try to push "sym" out to the leaves of a coercion. But,
how do we push sym into a ForAllCo? It's a little ugly.

Here is the typing rule:

h : k1 ~# k2
(tv : k1) |- g : ty1 ~# ty2
----------------------------
ForAllCo tv h g : (ForAllTy (tv : k1) ty1) ~#
                  (ForAllTy (tv : k2) (ty2[tv |-> tv |> sym h]))

Here is what we want:

ForAllCo tv h' g' : (ForAllTy (tv : k2) (ty2[tv |-> tv |> sym h])) ~#
                    (ForAllTy (tv : k1) ty1)


Because the kinds of the type variables to the right of the colon are the kinds
coerced by h', we know (h' : k2 ~# k1). Thus, (h' = sym h).

Now, we can rewrite ty1 to be (ty1[tv |-> tv |> sym h' |> h']). We thus want

ForAllCo tv h' g' :
  (ForAllTy (tv : k2) (ty2[tv |-> tv |> h'])) ~#
  (ForAllTy (tv : k1) (ty1[tv |-> tv |> h'][tv |-> tv |> sym h']))

We thus see that we want

g' : ty2[tv |-> tv |> h'] ~# ty1[tv |-> tv |> h']

and thus g' = sym (g[tv |-> tv |> h']).

Putting it all together, we get this:

sym (ForAllCo tv h g)
==>
ForAllCo tv (sym h) (sym g[tv |-> tv |> sym h])

Note [Substituting in a coercion hole]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
It seems highly suspicious to be substituting in a coercion that still
has coercion holes. Yet, this can happen in a situation like this:

  f :: forall k. k :~: Type -> ()
  f Refl = let x :: forall (a :: k). [a] -> ...
               x = ...

When we check x's type signature, we require that k ~ Type. We indeed
know this due to the Refl pattern match, but the eager unifier can't
make use of givens. So, when we're done looking at x's type, a coercion
hole will remain. Then, when we're checking x's definition, we skolemise
x's type (in order to, e.g., bring the scoped type variable `a` into scope).
This requires performing a substitution for the fresh skolem variables.

This subsitution needs to affect the kind of the coercion hole, too --
otherwise, the kind will have an out-of-scope variable in it. More problematically
in practice (we won't actually notice the out-of-scope variable ever), skolems
in the kind might have too high a level, triggering a failure to uphold the
invariant that no free variables in a type have a higher level than the
ambient level in the type checker. In the event of having free variables in the
hole's kind, I'm pretty sure we'll always have an erroneous program, so we
don't need to worry what will happen when the hole gets filled in. After all,
a hole relating a locally-bound type variable will be unable to be solved. This
is why it's OK not to look through the IORef of a coercion hole during
substitution.

-}

-- | Type substitution, see 'zipTvSubst'
substTyWith :: HasCallStack => [TyVar] -> [Type] -> Type -> Type
-- Works only if the domain of the substitution is a
-- superset of the type being substituted into
substTyWith :: [Var] -> [Type] -> Type -> Type
substTyWith [Var]
tvs [Type]
tys = {-#SCC "substTyWith" #-}
                      ASSERT( tvs `equalLength` tys )
                      HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy ([Var] -> [Type] -> TCvSubst
HasDebugCallStack => [Var] -> [Type] -> TCvSubst
zipTvSubst [Var]
tvs [Type]
tys)

-- | Type substitution, see 'zipTvSubst'. Disables sanity checks.
-- The problems that the sanity checks in substTy catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substTyUnchecked to
-- substTy and remove this function. Please don't use in new code.
substTyWithUnchecked :: [TyVar] -> [Type] -> Type -> Type
substTyWithUnchecked :: [Var] -> [Type] -> Type -> Type
substTyWithUnchecked [Var]
tvs [Type]
tys
  = ASSERT( tvs `equalLength` tys )
    TCvSubst -> Type -> Type
substTyUnchecked ([Var] -> [Type] -> TCvSubst
HasDebugCallStack => [Var] -> [Type] -> TCvSubst
zipTvSubst [Var]
tvs [Type]
tys)

-- | Substitute tyvars within a type using a known 'InScopeSet'.
-- Pre-condition: the 'in_scope' set should satisfy Note [The substitution
-- invariant]; specifically it should include the free vars of 'tys',
-- and of 'ty' minus the domain of the subst.
substTyWithInScope :: InScopeSet -> [TyVar] -> [Type] -> Type -> Type
substTyWithInScope :: InScopeSet -> [Var] -> [Type] -> Type -> Type
substTyWithInScope InScopeSet
in_scope [Var]
tvs [Type]
tys Type
ty =
  ASSERT( tvs `equalLength` tys )
  HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy (InScopeSet -> TvSubstEnv -> TCvSubst
mkTvSubst InScopeSet
in_scope TvSubstEnv
tenv) Type
ty
  where tenv :: TvSubstEnv
tenv = [Var] -> [Type] -> TvSubstEnv
HasDebugCallStack => [Var] -> [Type] -> TvSubstEnv
zipTyEnv [Var]
tvs [Type]
tys

-- | Coercion substitution, see 'zipTvSubst'
substCoWith :: HasCallStack => [TyVar] -> [Type] -> Coercion -> Coercion
substCoWith :: [Var] -> [Type] -> Coercion -> Coercion
substCoWith [Var]
tvs [Type]
tys = ASSERT( tvs `equalLength` tys )
                      HasCallStack => TCvSubst -> Coercion -> Coercion
TCvSubst -> Coercion -> Coercion
substCo ([Var] -> [Type] -> TCvSubst
HasDebugCallStack => [Var] -> [Type] -> TCvSubst
zipTvSubst [Var]
tvs [Type]
tys)

-- | Coercion substitution, see 'zipTvSubst'. Disables sanity checks.
-- The problems that the sanity checks in substCo catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substCoUnchecked to
-- substCo and remove this function. Please don't use in new code.
substCoWithUnchecked :: [TyVar] -> [Type] -> Coercion -> Coercion
substCoWithUnchecked :: [Var] -> [Type] -> Coercion -> Coercion
substCoWithUnchecked [Var]
tvs [Type]
tys
  = ASSERT( tvs `equalLength` tys )
    TCvSubst -> Coercion -> Coercion
substCoUnchecked ([Var] -> [Type] -> TCvSubst
HasDebugCallStack => [Var] -> [Type] -> TCvSubst
zipTvSubst [Var]
tvs [Type]
tys)



-- | Substitute covars within a type
substTyWithCoVars :: [CoVar] -> [Coercion] -> Type -> Type
substTyWithCoVars :: [Var] -> [Coercion] -> Type -> Type
substTyWithCoVars [Var]
cvs [Coercion]
cos = HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy ([Var] -> [Coercion] -> TCvSubst
HasDebugCallStack => [Var] -> [Coercion] -> TCvSubst
zipCvSubst [Var]
cvs [Coercion]
cos)

-- | Type substitution, see 'zipTvSubst'
substTysWith :: [TyVar] -> [Type] -> [Type] -> [Type]
substTysWith :: [Var] -> [Type] -> [Type] -> [Type]
substTysWith [Var]
tvs [Type]
tys = ASSERT( tvs `equalLength` tys )
                       HasCallStack => TCvSubst -> [Type] -> [Type]
TCvSubst -> [Type] -> [Type]
substTys ([Var] -> [Type] -> TCvSubst
HasDebugCallStack => [Var] -> [Type] -> TCvSubst
zipTvSubst [Var]
tvs [Type]
tys)

-- | Type substitution, see 'zipTvSubst'
substTysWithCoVars :: [CoVar] -> [Coercion] -> [Type] -> [Type]
substTysWithCoVars :: [Var] -> [Coercion] -> [Type] -> [Type]
substTysWithCoVars [Var]
cvs [Coercion]
cos = ASSERT( cvs `equalLength` cos )
                             HasCallStack => TCvSubst -> [Type] -> [Type]
TCvSubst -> [Type] -> [Type]
substTys ([Var] -> [Coercion] -> TCvSubst
HasDebugCallStack => [Var] -> [Coercion] -> TCvSubst
zipCvSubst [Var]
cvs [Coercion]
cos)

-- | Substitute within a 'Type' after adding the free variables of the type
-- to the in-scope set. This is useful for the case when the free variables
-- aren't already in the in-scope set or easily available.
-- See also Note [The substitution invariant].
substTyAddInScope :: TCvSubst -> Type -> Type
substTyAddInScope :: TCvSubst -> Type -> Type
substTyAddInScope TCvSubst
subst Type
ty =
  HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy (TCvSubst -> VarSet -> TCvSubst
extendTCvInScopeSet TCvSubst
subst (VarSet -> TCvSubst) -> VarSet -> TCvSubst
forall a b. (a -> b) -> a -> b
$ Type -> VarSet
tyCoVarsOfType Type
ty) Type
ty

-- | When calling `substTy` it should be the case that the in-scope set in
-- the substitution is a superset of the free vars of the range of the
-- substitution.
-- See also Note [The substitution invariant].
isValidTCvSubst :: TCvSubst -> Bool
isValidTCvSubst :: TCvSubst -> Bool
isValidTCvSubst (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) =
  (VarSet
tenvFVs VarSet -> InScopeSet -> Bool
`varSetInScope` InScopeSet
in_scope) Bool -> Bool -> Bool
&&
  (VarSet
cenvFVs VarSet -> InScopeSet -> Bool
`varSetInScope` InScopeSet
in_scope)
  where
  tenvFVs :: VarSet
tenvFVs = TvSubstEnv -> VarSet
tyCoVarsOfTypesSet TvSubstEnv
tenv
  cenvFVs :: VarSet
cenvFVs = CvSubstEnv -> VarSet
tyCoVarsOfCosSet CvSubstEnv
cenv

-- | This checks if the substitution satisfies the invariant from
-- Note [The substitution invariant].
checkValidSubst :: HasCallStack => TCvSubst -> [Type] -> [Coercion] -> a -> a
checkValidSubst :: TCvSubst -> [Type] -> [Coercion] -> a -> a
checkValidSubst subst :: TCvSubst
subst@(TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) [Type]
tys [Coercion]
cos a
a
  = ASSERT2( isValidTCvSubst subst,
             text "in_scope" <+> ppr in_scope $$
             text "tenv" <+> ppr tenv $$
             text "tenvFVs" <+> ppr (tyCoVarsOfTypesSet tenv) $$
             text "cenv" <+> ppr cenv $$
             text "cenvFVs" <+> ppr (tyCoVarsOfCosSet cenv) $$
             text "tys" <+> ppr tys $$
             text "cos" <+> ppr cos )
    ASSERT2( tysCosFVsInScope,
             text "in_scope" <+> ppr in_scope $$
             text "tenv" <+> ppr tenv $$
             text "cenv" <+> ppr cenv $$
             text "tys" <+> ppr tys $$
             text "cos" <+> ppr cos $$
             text "needInScope" <+> ppr needInScope )
    a
a
  where
  substDomain :: [Unique]
substDomain = TvSubstEnv -> [Unique]
forall elt. UniqFM elt -> [Unique]
nonDetKeysUFM TvSubstEnv
tenv [Unique] -> [Unique] -> [Unique]
forall a. [a] -> [a] -> [a]
++ CvSubstEnv -> [Unique]
forall elt. UniqFM elt -> [Unique]
nonDetKeysUFM CvSubstEnv
cenv
    -- It's OK to use nonDetKeysUFM here, because we only use this list to
    -- remove some elements from a set
  needInScope :: VarSet
needInScope = ([Type] -> VarSet
tyCoVarsOfTypes [Type]
tys VarSet -> VarSet -> VarSet
`unionVarSet` [Coercion] -> VarSet
tyCoVarsOfCos [Coercion]
cos)
                  VarSet -> [Unique] -> VarSet
forall a. UniqSet a -> [Unique] -> UniqSet a
`delListFromUniqSet_Directly` [Unique]
substDomain
  tysCosFVsInScope :: Bool
tysCosFVsInScope = VarSet
needInScope VarSet -> InScopeSet -> Bool
`varSetInScope` InScopeSet
in_scope


-- | Substitute within a 'Type'
-- The substitution has to satisfy the invariants described in
-- Note [The substitution invariant].
substTy :: HasCallStack => TCvSubst -> Type  -> Type
substTy :: TCvSubst -> Type -> Type
substTy TCvSubst
subst Type
ty
  | TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst = Type
ty
  | Bool
otherwise             = TCvSubst -> [Type] -> [Coercion] -> Type -> Type
forall a.
HasCallStack =>
TCvSubst -> [Type] -> [Coercion] -> a -> a
checkValidSubst TCvSubst
subst [Type
ty] [] (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$
                            TCvSubst -> Type -> Type
subst_ty TCvSubst
subst Type
ty

-- | Substitute within a 'Type' disabling the sanity checks.
-- The problems that the sanity checks in substTy catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substTyUnchecked to
-- substTy and remove this function. Please don't use in new code.
substTyUnchecked :: TCvSubst -> Type -> Type
substTyUnchecked :: TCvSubst -> Type -> Type
substTyUnchecked TCvSubst
subst Type
ty
                 | TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst = Type
ty
                 | Bool
otherwise             = TCvSubst -> Type -> Type
subst_ty TCvSubst
subst Type
ty

-- | Substitute within several 'Type's
-- The substitution has to satisfy the invariants described in
-- Note [The substitution invariant].
substTys :: HasCallStack => TCvSubst -> [Type] -> [Type]
substTys :: TCvSubst -> [Type] -> [Type]
substTys TCvSubst
subst [Type]
tys
  | TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst = [Type]
tys
  | Bool
otherwise = TCvSubst -> [Type] -> [Coercion] -> [Type] -> [Type]
forall a.
HasCallStack =>
TCvSubst -> [Type] -> [Coercion] -> a -> a
checkValidSubst TCvSubst
subst [Type]
tys [] ([Type] -> [Type]) -> [Type] -> [Type]
forall a b. (a -> b) -> a -> b
$ (Type -> Type) -> [Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> Type -> Type
subst_ty TCvSubst
subst) [Type]
tys

-- | Substitute within several 'Type's disabling the sanity checks.
-- The problems that the sanity checks in substTys catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substTysUnchecked to
-- substTys and remove this function. Please don't use in new code.
substTysUnchecked :: TCvSubst -> [Type] -> [Type]
substTysUnchecked :: TCvSubst -> [Type] -> [Type]
substTysUnchecked TCvSubst
subst [Type]
tys
                 | TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst = [Type]
tys
                 | Bool
otherwise             = (Type -> Type) -> [Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> Type -> Type
subst_ty TCvSubst
subst) [Type]
tys

-- | Substitute within a 'ThetaType'
-- The substitution has to satisfy the invariants described in
-- Note [The substitution invariant].
substTheta :: HasCallStack => TCvSubst -> ThetaType -> ThetaType
substTheta :: TCvSubst -> [Type] -> [Type]
substTheta = HasCallStack => TCvSubst -> [Type] -> [Type]
TCvSubst -> [Type] -> [Type]
substTys

-- | Substitute within a 'ThetaType' disabling the sanity checks.
-- The problems that the sanity checks in substTys catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substThetaUnchecked to
-- substTheta and remove this function. Please don't use in new code.
substThetaUnchecked :: TCvSubst -> ThetaType -> ThetaType
substThetaUnchecked :: TCvSubst -> [Type] -> [Type]
substThetaUnchecked = TCvSubst -> [Type] -> [Type]
substTysUnchecked


subst_ty :: TCvSubst -> Type -> Type
-- subst_ty is the main workhorse for type substitution
--
-- Note that the in_scope set is poked only if we hit a forall
-- so it may often never be fully computed
subst_ty :: TCvSubst -> Type -> Type
subst_ty TCvSubst
subst Type
ty
   = Type -> Type
go Type
ty
  where
    go :: Type -> Type
go (TyVarTy Var
tv)      = TCvSubst -> Var -> Type
substTyVar TCvSubst
subst Var
tv
    go (AppTy Type
fun Type
arg)   = Type -> Type -> Type
mkAppTy (Type -> Type
go Type
fun) (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$! (Type -> Type
go Type
arg)
                -- The mkAppTy smart constructor is important
                -- we might be replacing (a Int), represented with App
                -- by [Int], represented with TyConApp
    go (TyConApp TyCon
tc [Type]
tys) = let args :: [Type]
args = (Type -> Type) -> [Type] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map Type -> Type
go [Type]
tys
                           in  [Type]
args [Type] -> Type -> Type
forall a b. [a] -> b -> b
`seqList` TyCon -> [Type] -> Type
TyConApp TyCon
tc [Type]
args
    go ty :: Type
ty@(FunTy { ft_arg :: Type -> Type
ft_arg = Type
arg, ft_res :: Type -> Type
ft_res = Type
res })
      = let !arg' :: Type
arg' = Type -> Type
go Type
arg
            !res' :: Type
res' = Type -> Type
go Type
res
        in Type
ty { ft_arg :: Type
ft_arg = Type
arg', ft_res :: Type
ft_res = Type
res' }
    go (ForAllTy (Bndr Var
tv ArgFlag
vis) Type
ty)
                         = case TCvSubst -> Var -> (TCvSubst, Var)
substVarBndrUnchecked TCvSubst
subst Var
tv of
                             (TCvSubst
subst', Var
tv') ->
                               (VarBndr Var ArgFlag -> Type -> Type
ForAllTy (VarBndr Var ArgFlag -> Type -> Type)
-> VarBndr Var ArgFlag -> Type -> Type
forall a b. (a -> b) -> a -> b
$! ((Var -> ArgFlag -> VarBndr Var ArgFlag
forall var argf. var -> argf -> VarBndr var argf
Bndr (Var -> ArgFlag -> VarBndr Var ArgFlag)
-> Var -> ArgFlag -> VarBndr Var ArgFlag
forall a b. (a -> b) -> a -> b
$! Var
tv') ArgFlag
vis)) (Type -> Type) -> Type -> Type
forall a b. (a -> b) -> a -> b
$!
                                            (TCvSubst -> Type -> Type
subst_ty TCvSubst
subst' Type
ty)
    go (LitTy TyLit
n)         = TyLit -> Type
LitTy (TyLit -> Type) -> TyLit -> Type
forall a b. (a -> b) -> a -> b
$! TyLit
n
    go (CastTy Type
ty Coercion
co)    = (Type -> Coercion -> Type
mkCastTy (Type -> Coercion -> Type) -> Type -> Coercion -> Type
forall a b. (a -> b) -> a -> b
$! (Type -> Type
go Type
ty)) (Coercion -> Type) -> Coercion -> Type
forall a b. (a -> b) -> a -> b
$! (TCvSubst -> Coercion -> Coercion
subst_co TCvSubst
subst Coercion
co)
    go (CoercionTy Coercion
co)   = Coercion -> Type
CoercionTy (Coercion -> Type) -> Coercion -> Type
forall a b. (a -> b) -> a -> b
$! (TCvSubst -> Coercion -> Coercion
subst_co TCvSubst
subst Coercion
co)

substTyVar :: TCvSubst -> TyVar -> Type
substTyVar :: TCvSubst -> Var -> Type
substTyVar (TCvSubst InScopeSet
_ TvSubstEnv
tenv CvSubstEnv
_) Var
tv
  = ASSERT( isTyVar tv )
    case TvSubstEnv -> Var -> Maybe Type
forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv TvSubstEnv
tenv Var
tv of
      Just Type
ty -> Type
ty
      Maybe Type
Nothing -> Var -> Type
TyVarTy Var
tv

substTyVars :: TCvSubst -> [TyVar] -> [Type]
substTyVars :: TCvSubst -> [Var] -> [Type]
substTyVars TCvSubst
subst = (Var -> Type) -> [Var] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map ((Var -> Type) -> [Var] -> [Type])
-> (Var -> Type) -> [Var] -> [Type]
forall a b. (a -> b) -> a -> b
$ TCvSubst -> Var -> Type
substTyVar TCvSubst
subst

substTyCoVars :: TCvSubst -> [TyCoVar] -> [Type]
substTyCoVars :: TCvSubst -> [Var] -> [Type]
substTyCoVars TCvSubst
subst = (Var -> Type) -> [Var] -> [Type]
forall a b. (a -> b) -> [a] -> [b]
map ((Var -> Type) -> [Var] -> [Type])
-> (Var -> Type) -> [Var] -> [Type]
forall a b. (a -> b) -> a -> b
$ TCvSubst -> Var -> Type
substTyCoVar TCvSubst
subst

substTyCoVar :: TCvSubst -> TyCoVar -> Type
substTyCoVar :: TCvSubst -> Var -> Type
substTyCoVar TCvSubst
subst Var
tv
  | Var -> Bool
isTyVar Var
tv = TCvSubst -> Var -> Type
substTyVar TCvSubst
subst Var
tv
  | Bool
otherwise = Coercion -> Type
CoercionTy (Coercion -> Type) -> Coercion -> Type
forall a b. (a -> b) -> a -> b
$ TCvSubst -> Var -> Coercion
substCoVar TCvSubst
subst Var
tv

lookupTyVar :: TCvSubst -> TyVar  -> Maybe Type
        -- See Note [Extending the TCvSubst]
lookupTyVar :: TCvSubst -> Var -> Maybe Type
lookupTyVar (TCvSubst InScopeSet
_ TvSubstEnv
tenv CvSubstEnv
_) Var
tv
  = ASSERT( isTyVar tv )
    TvSubstEnv -> Var -> Maybe Type
forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv TvSubstEnv
tenv Var
tv

-- | Substitute within a 'Coercion'
-- The substitution has to satisfy the invariants described in
-- Note [The substitution invariant].
substCo :: HasCallStack => TCvSubst -> Coercion -> Coercion
substCo :: TCvSubst -> Coercion -> Coercion
substCo TCvSubst
subst Coercion
co
  | TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst = Coercion
co
  | Bool
otherwise = TCvSubst -> [Type] -> [Coercion] -> Coercion -> Coercion
forall a.
HasCallStack =>
TCvSubst -> [Type] -> [Coercion] -> a -> a
checkValidSubst TCvSubst
subst [] [Coercion
co] (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$ TCvSubst -> Coercion -> Coercion
subst_co TCvSubst
subst Coercion
co

-- | Substitute within a 'Coercion' disabling sanity checks.
-- The problems that the sanity checks in substCo catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substCoUnchecked to
-- substCo and remove this function. Please don't use in new code.
substCoUnchecked :: TCvSubst -> Coercion -> Coercion
substCoUnchecked :: TCvSubst -> Coercion -> Coercion
substCoUnchecked TCvSubst
subst Coercion
co
  | TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst = Coercion
co
  | Bool
otherwise = TCvSubst -> Coercion -> Coercion
subst_co TCvSubst
subst Coercion
co

-- | Substitute within several 'Coercion's
-- The substitution has to satisfy the invariants described in
-- Note [The substitution invariant].
substCos :: HasCallStack => TCvSubst -> [Coercion] -> [Coercion]
substCos :: TCvSubst -> [Coercion] -> [Coercion]
substCos TCvSubst
subst [Coercion]
cos
  | TCvSubst -> Bool
isEmptyTCvSubst TCvSubst
subst = [Coercion]
cos
  | Bool
otherwise = TCvSubst -> [Type] -> [Coercion] -> [Coercion] -> [Coercion]
forall a.
HasCallStack =>
TCvSubst -> [Type] -> [Coercion] -> a -> a
checkValidSubst TCvSubst
subst [] [Coercion]
cos ([Coercion] -> [Coercion]) -> [Coercion] -> [Coercion]
forall a b. (a -> b) -> a -> b
$ (Coercion -> Coercion) -> [Coercion] -> [Coercion]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> Coercion -> Coercion
subst_co TCvSubst
subst) [Coercion]
cos

subst_co :: TCvSubst -> Coercion -> Coercion
subst_co :: TCvSubst -> Coercion -> Coercion
subst_co TCvSubst
subst Coercion
co
  = Coercion -> Coercion
go Coercion
co
  where
    go_ty :: Type -> Type
    go_ty :: Type -> Type
go_ty = TCvSubst -> Type -> Type
subst_ty TCvSubst
subst

    go_mco :: MCoercion -> MCoercion
    go_mco :: MCoercion -> MCoercion
go_mco MCoercion
MRefl    = MCoercion
MRefl
    go_mco (MCo Coercion
co) = Coercion -> MCoercion
MCo (Coercion -> Coercion
go Coercion
co)

    go :: Coercion -> Coercion
    go :: Coercion -> Coercion
go (Refl Type
ty)             = Type -> Coercion
mkNomReflCo (Type -> Coercion) -> Type -> Coercion
forall a b. (a -> b) -> a -> b
$! (Type -> Type
go_ty Type
ty)
    go (GRefl Role
r Type
ty MCoercion
mco)      = (Role -> Type -> MCoercion -> Coercion
mkGReflCo Role
r (Type -> MCoercion -> Coercion) -> Type -> MCoercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Type -> Type
go_ty Type
ty)) (MCoercion -> Coercion) -> MCoercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (MCoercion -> MCoercion
go_mco MCoercion
mco)
    go (TyConAppCo Role
r TyCon
tc [Coercion]
args)= let args' :: [Coercion]
args' = (Coercion -> Coercion) -> [Coercion] -> [Coercion]
forall a b. (a -> b) -> [a] -> [b]
map Coercion -> Coercion
go [Coercion]
args
                               in  [Coercion]
args' [Coercion] -> Coercion -> Coercion
forall a b. [a] -> b -> b
`seqList` HasDebugCallStack => Role -> TyCon -> [Coercion] -> Coercion
Role -> TyCon -> [Coercion] -> Coercion
mkTyConAppCo Role
r TyCon
tc [Coercion]
args'
    go (AppCo Coercion
co Coercion
arg)        = (Coercion -> Coercion -> Coercion
mkAppCo (Coercion -> Coercion -> Coercion)
-> Coercion -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! Coercion -> Coercion
go Coercion
co) (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! Coercion -> Coercion
go Coercion
arg
    go (ForAllCo Var
tv Coercion
kind_co Coercion
co)
      = case TCvSubst -> Var -> Coercion -> (TCvSubst, Var, Coercion)
substForAllCoBndrUnchecked TCvSubst
subst Var
tv Coercion
kind_co of
         (TCvSubst
subst', Var
tv', Coercion
kind_co') ->
          ((Var -> Coercion -> Coercion -> Coercion
mkForAllCo (Var -> Coercion -> Coercion -> Coercion)
-> Var -> Coercion -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! Var
tv') (Coercion -> Coercion -> Coercion)
-> Coercion -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! Coercion
kind_co') (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! TCvSubst -> Coercion -> Coercion
subst_co TCvSubst
subst' Coercion
co
    go (FunCo Role
r Coercion
co1 Coercion
co2)     = (Role -> Coercion -> Coercion -> Coercion
mkFunCo Role
r (Coercion -> Coercion -> Coercion)
-> Coercion -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! Coercion -> Coercion
go Coercion
co1) (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! Coercion -> Coercion
go Coercion
co2
    go (CoVarCo Var
cv)          = TCvSubst -> Var -> Coercion
substCoVar TCvSubst
subst Var
cv
    go (AxiomInstCo CoAxiom Branched
con Int
ind [Coercion]
cos) = CoAxiom Branched -> Int -> [Coercion] -> Coercion
mkAxiomInstCo CoAxiom Branched
con Int
ind ([Coercion] -> Coercion) -> [Coercion] -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion) -> [Coercion] -> [Coercion]
forall a b. (a -> b) -> [a] -> [b]
map Coercion -> Coercion
go [Coercion]
cos
    go (UnivCo UnivCoProvenance
p Role
r Type
t1 Type
t2)    = (((UnivCoProvenance -> Role -> Type -> Type -> Coercion
mkUnivCo (UnivCoProvenance -> Role -> Type -> Type -> Coercion)
-> UnivCoProvenance -> Role -> Type -> Type -> Coercion
forall a b. (a -> b) -> a -> b
$! UnivCoProvenance -> UnivCoProvenance
go_prov UnivCoProvenance
p) (Role -> Type -> Type -> Coercion)
-> Role -> Type -> Type -> Coercion
forall a b. (a -> b) -> a -> b
$! Role
r) (Type -> Type -> Coercion) -> Type -> Type -> Coercion
forall a b. (a -> b) -> a -> b
$!
                                (Type -> Type
go_ty Type
t1)) (Type -> Coercion) -> Type -> Coercion
forall a b. (a -> b) -> a -> b
$! (Type -> Type
go_ty Type
t2)
    go (SymCo Coercion
co)            = Coercion -> Coercion
mkSymCo (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co)
    go (TransCo Coercion
co1 Coercion
co2)     = (Coercion -> Coercion -> Coercion
mkTransCo (Coercion -> Coercion -> Coercion)
-> Coercion -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co1)) (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co2)
    go (NthCo Role
r Int
d Coercion
co)        = HasDebugCallStack => Role -> Int -> Coercion -> Coercion
Role -> Int -> Coercion -> Coercion
mkNthCo Role
r Int
d (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co)
    go (LRCo LeftOrRight
lr Coercion
co)          = LeftOrRight -> Coercion -> Coercion
mkLRCo LeftOrRight
lr (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co)
    go (InstCo Coercion
co Coercion
arg)       = (Coercion -> Coercion -> Coercion
mkInstCo (Coercion -> Coercion -> Coercion)
-> Coercion -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co)) (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! Coercion -> Coercion
go Coercion
arg
    go (KindCo Coercion
co)           = Coercion -> Coercion
mkKindCo (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co)
    go (SubCo Coercion
co)            = Coercion -> Coercion
mkSubCo (Coercion -> Coercion) -> Coercion -> Coercion
forall a b. (a -> b) -> a -> b
$! (Coercion -> Coercion
go Coercion
co)
    go (AxiomRuleCo CoAxiomRule
c [Coercion]
cs)    = let cs1 :: [Coercion]
cs1 = (Coercion -> Coercion) -> [Coercion] -> [Coercion]
forall a b. (a -> b) -> [a] -> [b]
map Coercion -> Coercion
go [Coercion]
cs
                                in [Coercion]
cs1 [Coercion] -> Coercion -> Coercion
forall a b. [a] -> b -> b
`seqList` CoAxiomRule -> [Coercion] -> Coercion
AxiomRuleCo CoAxiomRule
c [Coercion]
cs1
    go (HoleCo CoercionHole
h)            = CoercionHole -> Coercion
HoleCo (CoercionHole -> Coercion) -> CoercionHole -> Coercion
forall a b. (a -> b) -> a -> b
$! CoercionHole -> CoercionHole
go_hole CoercionHole
h

    go_prov :: UnivCoProvenance -> UnivCoProvenance
go_prov UnivCoProvenance
UnsafeCoerceProv     = UnivCoProvenance
UnsafeCoerceProv
    go_prov (PhantomProv Coercion
kco)    = Coercion -> UnivCoProvenance
PhantomProv (Coercion -> Coercion
go Coercion
kco)
    go_prov (ProofIrrelProv Coercion
kco) = Coercion -> UnivCoProvenance
ProofIrrelProv (Coercion -> Coercion
go Coercion
kco)
    go_prov p :: UnivCoProvenance
p@(PluginProv String
_)     = UnivCoProvenance
p

    -- See Note [Substituting in a coercion hole]
    go_hole :: CoercionHole -> CoercionHole
go_hole h :: CoercionHole
h@(CoercionHole { ch_co_var :: CoercionHole -> Var
ch_co_var = Var
cv })
      = CoercionHole
h { ch_co_var :: Var
ch_co_var = (Type -> Type) -> Var -> Var
updateVarType Type -> Type
go_ty Var
cv }

substForAllCoBndr :: TCvSubst -> TyCoVar -> KindCoercion
                  -> (TCvSubst, TyCoVar, Coercion)
substForAllCoBndr :: TCvSubst -> Var -> Coercion -> (TCvSubst, Var, Coercion)
substForAllCoBndr TCvSubst
subst
  = Bool
-> (Coercion -> Coercion)
-> TCvSubst
-> Var
-> Coercion
-> (TCvSubst, Var, Coercion)
substForAllCoBndrUsing Bool
False (HasCallStack => TCvSubst -> Coercion -> Coercion
TCvSubst -> Coercion -> Coercion
substCo TCvSubst
subst) TCvSubst
subst

-- | Like 'substForAllCoBndr', but disables sanity checks.
-- The problems that the sanity checks in substCo catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substCoUnchecked to
-- substCo and remove this function. Please don't use in new code.
substForAllCoBndrUnchecked :: TCvSubst -> TyCoVar -> KindCoercion
                           -> (TCvSubst, TyCoVar, Coercion)
substForAllCoBndrUnchecked :: TCvSubst -> Var -> Coercion -> (TCvSubst, Var, Coercion)
substForAllCoBndrUnchecked TCvSubst
subst
  = Bool
-> (Coercion -> Coercion)
-> TCvSubst
-> Var
-> Coercion
-> (TCvSubst, Var, Coercion)
substForAllCoBndrUsing Bool
False (TCvSubst -> Coercion -> Coercion
substCoUnchecked TCvSubst
subst) TCvSubst
subst

-- See Note [Sym and ForAllCo]
substForAllCoBndrUsing :: Bool  -- apply sym to binder?
                       -> (Coercion -> Coercion)  -- transformation to kind co
                       -> TCvSubst -> TyCoVar -> KindCoercion
                       -> (TCvSubst, TyCoVar, KindCoercion)
substForAllCoBndrUsing :: Bool
-> (Coercion -> Coercion)
-> TCvSubst
-> Var
-> Coercion
-> (TCvSubst, Var, Coercion)
substForAllCoBndrUsing Bool
sym Coercion -> Coercion
sco TCvSubst
subst Var
old_var
  | Var -> Bool
isTyVar Var
old_var = Bool
-> (Coercion -> Coercion)
-> TCvSubst
-> Var
-> Coercion
-> (TCvSubst, Var, Coercion)
substForAllCoTyVarBndrUsing Bool
sym Coercion -> Coercion
sco TCvSubst
subst Var
old_var
  | Bool
otherwise       = Bool
-> (Coercion -> Coercion)
-> TCvSubst
-> Var
-> Coercion
-> (TCvSubst, Var, Coercion)
substForAllCoCoVarBndrUsing Bool
sym Coercion -> Coercion
sco TCvSubst
subst Var
old_var

substForAllCoTyVarBndrUsing :: Bool  -- apply sym to binder?
                            -> (Coercion -> Coercion)  -- transformation to kind co
                            -> TCvSubst -> TyVar -> KindCoercion
                            -> (TCvSubst, TyVar, KindCoercion)
substForAllCoTyVarBndrUsing :: Bool
-> (Coercion -> Coercion)
-> TCvSubst
-> Var
-> Coercion
-> (TCvSubst, Var, Coercion)
substForAllCoTyVarBndrUsing Bool
sym Coercion -> Coercion
sco (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
old_var Coercion
old_kind_co
  = ASSERT( isTyVar old_var )
    ( InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet
in_scope InScopeSet -> Var -> InScopeSet
`extendInScopeSet` Var
new_var) TvSubstEnv
new_env CvSubstEnv
cenv
    , Var
new_var, Coercion
new_kind_co )
  where
    new_env :: TvSubstEnv
new_env | Bool
no_change Bool -> Bool -> Bool
&& Bool -> Bool
not Bool
sym = TvSubstEnv -> Var -> TvSubstEnv
forall a. VarEnv a -> Var -> VarEnv a
delVarEnv TvSubstEnv
tenv Var
old_var
            | Bool
sym       = TvSubstEnv -> Var -> Type -> TvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv TvSubstEnv
tenv Var
old_var (Type -> TvSubstEnv) -> Type -> TvSubstEnv
forall a b. (a -> b) -> a -> b
$
                          Var -> Type
TyVarTy Var
new_var Type -> Coercion -> Type
`CastTy` Coercion
new_kind_co
            | Bool
otherwise = TvSubstEnv -> Var -> Type -> TvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv TvSubstEnv
tenv Var
old_var (Var -> Type
TyVarTy Var
new_var)

    no_kind_change :: Bool
no_kind_change = Coercion -> Bool
noFreeVarsOfCo Coercion
old_kind_co
    no_change :: Bool
no_change = Bool
no_kind_change Bool -> Bool -> Bool
&& (Var
new_var Var -> Var -> Bool
forall a. Eq a => a -> a -> Bool
== Var
old_var)

    new_kind_co :: Coercion
new_kind_co | Bool
no_kind_change = Coercion
old_kind_co
                | Bool
otherwise      = Coercion -> Coercion
sco Coercion
old_kind_co

    Pair Type
new_ki1 Type
_ = Coercion -> Pair Type
coercionKind Coercion
new_kind_co
    -- We could do substitution to (tyVarKind old_var). We don't do so because
    -- we already substituted new_kind_co, which contains the kind information
    -- we want. We don't want to do substitution once more. Also, in most cases,
    -- new_kind_co is a Refl, in which case coercionKind is really fast.

    new_var :: Var
new_var  = InScopeSet -> Var -> Var
uniqAway InScopeSet
in_scope (Var -> Type -> Var
setTyVarKind Var
old_var Type
new_ki1)

substForAllCoCoVarBndrUsing :: Bool  -- apply sym to binder?
                            -> (Coercion -> Coercion)  -- transformation to kind co
                            -> TCvSubst -> CoVar -> KindCoercion
                            -> (TCvSubst, CoVar, KindCoercion)
substForAllCoCoVarBndrUsing :: Bool
-> (Coercion -> Coercion)
-> TCvSubst
-> Var
-> Coercion
-> (TCvSubst, Var, Coercion)
substForAllCoCoVarBndrUsing Bool
sym Coercion -> Coercion
sco (TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv)
                            Var
old_var Coercion
old_kind_co
  = ASSERT( isCoVar old_var )
    ( InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet
in_scope InScopeSet -> Var -> InScopeSet
`extendInScopeSet` Var
new_var) TvSubstEnv
tenv CvSubstEnv
new_cenv
    , Var
new_var, Coercion
new_kind_co )
  where
    new_cenv :: CvSubstEnv
new_cenv | Bool
no_change Bool -> Bool -> Bool
&& Bool -> Bool
not Bool
sym = CvSubstEnv -> Var -> CvSubstEnv
forall a. VarEnv a -> Var -> VarEnv a
delVarEnv CvSubstEnv
cenv Var
old_var
             | Bool
otherwise = CvSubstEnv -> Var -> Coercion -> CvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv CvSubstEnv
cenv Var
old_var (Var -> Coercion
mkCoVarCo Var
new_var)

    no_kind_change :: Bool
no_kind_change = Coercion -> Bool
noFreeVarsOfCo Coercion
old_kind_co
    no_change :: Bool
no_change = Bool
no_kind_change Bool -> Bool -> Bool
&& (Var
new_var Var -> Var -> Bool
forall a. Eq a => a -> a -> Bool
== Var
old_var)

    new_kind_co :: Coercion
new_kind_co | Bool
no_kind_change = Coercion
old_kind_co
                | Bool
otherwise      = Coercion -> Coercion
sco Coercion
old_kind_co

    Pair Type
h1 Type
h2 = Coercion -> Pair Type
coercionKind Coercion
new_kind_co

    new_var :: Var
new_var       = InScopeSet -> Var -> Var
uniqAway InScopeSet
in_scope (Var -> Var) -> Var -> Var
forall a b. (a -> b) -> a -> b
$ Name -> Type -> Var
mkCoVar (Var -> Name
varName Var
old_var) Type
new_var_type
    new_var_type :: Type
new_var_type  | Bool
sym       = Type
h2
                  | Bool
otherwise = Type
h1

substCoVar :: TCvSubst -> CoVar -> Coercion
substCoVar :: TCvSubst -> Var -> Coercion
substCoVar (TCvSubst InScopeSet
_ TvSubstEnv
_ CvSubstEnv
cenv) Var
cv
  = case CvSubstEnv -> Var -> Maybe Coercion
forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv CvSubstEnv
cenv Var
cv of
      Just Coercion
co -> Coercion
co
      Maybe Coercion
Nothing -> Var -> Coercion
CoVarCo Var
cv

substCoVars :: TCvSubst -> [CoVar] -> [Coercion]
substCoVars :: TCvSubst -> [Var] -> [Coercion]
substCoVars TCvSubst
subst [Var]
cvs = (Var -> Coercion) -> [Var] -> [Coercion]
forall a b. (a -> b) -> [a] -> [b]
map (TCvSubst -> Var -> Coercion
substCoVar TCvSubst
subst) [Var]
cvs

lookupCoVar :: TCvSubst -> Var -> Maybe Coercion
lookupCoVar :: TCvSubst -> Var -> Maybe Coercion
lookupCoVar (TCvSubst InScopeSet
_ TvSubstEnv
_ CvSubstEnv
cenv) Var
v = CvSubstEnv -> Var -> Maybe Coercion
forall a. VarEnv a -> Var -> Maybe a
lookupVarEnv CvSubstEnv
cenv Var
v

substTyVarBndr :: HasCallStack => TCvSubst -> TyVar -> (TCvSubst, TyVar)
substTyVarBndr :: TCvSubst -> Var -> (TCvSubst, Var)
substTyVarBndr = (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substTyVarBndrUsing HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy

substTyVarBndrs :: HasCallStack => TCvSubst -> [TyVar] -> (TCvSubst, [TyVar])
substTyVarBndrs :: TCvSubst -> [Var] -> (TCvSubst, [Var])
substTyVarBndrs = (TCvSubst -> Var -> (TCvSubst, Var))
-> TCvSubst -> [Var] -> (TCvSubst, [Var])
forall (t :: * -> *) a b c.
Traversable t =>
(a -> b -> (a, c)) -> a -> t b -> (a, t c)
mapAccumL HasCallStack => TCvSubst -> Var -> (TCvSubst, Var)
TCvSubst -> Var -> (TCvSubst, Var)
substTyVarBndr

substVarBndr :: HasCallStack => TCvSubst -> TyCoVar -> (TCvSubst, TyCoVar)
substVarBndr :: TCvSubst -> Var -> (TCvSubst, Var)
substVarBndr = (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substVarBndrUsing HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy

substVarBndrs :: HasCallStack => TCvSubst -> [TyCoVar] -> (TCvSubst, [TyCoVar])
substVarBndrs :: TCvSubst -> [Var] -> (TCvSubst, [Var])
substVarBndrs = (TCvSubst -> Var -> (TCvSubst, Var))
-> TCvSubst -> [Var] -> (TCvSubst, [Var])
forall (t :: * -> *) a b c.
Traversable t =>
(a -> b -> (a, c)) -> a -> t b -> (a, t c)
mapAccumL HasCallStack => TCvSubst -> Var -> (TCvSubst, Var)
TCvSubst -> Var -> (TCvSubst, Var)
substVarBndr

substCoVarBndr :: HasCallStack => TCvSubst -> CoVar -> (TCvSubst, CoVar)
substCoVarBndr :: TCvSubst -> Var -> (TCvSubst, Var)
substCoVarBndr = (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substCoVarBndrUsing HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy

-- | Like 'substVarBndr', but disables sanity checks.
-- The problems that the sanity checks in substTy catch are described in
-- Note [The substitution invariant].
-- The goal of #11371 is to migrate all the calls of substTyUnchecked to
-- substTy and remove this function. Please don't use in new code.
substVarBndrUnchecked :: TCvSubst -> TyCoVar -> (TCvSubst, TyCoVar)
substVarBndrUnchecked :: TCvSubst -> Var -> (TCvSubst, Var)
substVarBndrUnchecked = (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substVarBndrUsing TCvSubst -> Type -> Type
substTyUnchecked

substVarBndrUsing :: (TCvSubst -> Type -> Type)
                  -> TCvSubst -> TyCoVar -> (TCvSubst, TyCoVar)
substVarBndrUsing :: (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substVarBndrUsing TCvSubst -> Type -> Type
subst_fn TCvSubst
subst Var
v
  | Var -> Bool
isTyVar Var
v = (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substTyVarBndrUsing TCvSubst -> Type -> Type
subst_fn TCvSubst
subst Var
v
  | Bool
otherwise = (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substCoVarBndrUsing TCvSubst -> Type -> Type
subst_fn TCvSubst
subst Var
v

-- | Substitute a tyvar in a binding position, returning an
-- extended subst and a new tyvar.
-- Use the supplied function to substitute in the kind
substTyVarBndrUsing
  :: (TCvSubst -> Type -> Type)  -- ^ Use this to substitute in the kind
  -> TCvSubst -> TyVar -> (TCvSubst, TyVar)
substTyVarBndrUsing :: (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substTyVarBndrUsing TCvSubst -> Type -> Type
subst_fn subst :: TCvSubst
subst@(TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
old_var
  = ASSERT2( _no_capture, pprTyVar old_var $$ pprTyVar new_var $$ ppr subst )
    ASSERT( isTyVar old_var )
    (InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet
in_scope InScopeSet -> Var -> InScopeSet
`extendInScopeSet` Var
new_var) TvSubstEnv
new_env CvSubstEnv
cenv, Var
new_var)
  where
    new_env :: TvSubstEnv
new_env | Bool
no_change = TvSubstEnv -> Var -> TvSubstEnv
forall a. VarEnv a -> Var -> VarEnv a
delVarEnv TvSubstEnv
tenv Var
old_var
            | Bool
otherwise = TvSubstEnv -> Var -> Type -> TvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv TvSubstEnv
tenv Var
old_var (Var -> Type
TyVarTy Var
new_var)

    _no_capture :: Bool
_no_capture = Bool -> Bool
not (Var
new_var Var -> VarSet -> Bool
`elemVarSet` TvSubstEnv -> VarSet
tyCoVarsOfTypesSet TvSubstEnv
tenv)
    -- Assertion check that we are not capturing something in the substitution

    old_ki :: Type
old_ki = Var -> Type
tyVarKind Var
old_var
    no_kind_change :: Bool
no_kind_change = Type -> Bool
noFreeVarsOfType Type
old_ki -- verify that kind is closed
    no_change :: Bool
no_change = Bool
no_kind_change Bool -> Bool -> Bool
&& (Var
new_var Var -> Var -> Bool
forall a. Eq a => a -> a -> Bool
== Var
old_var)
        -- no_change means that the new_var is identical in
        -- all respects to the old_var (same unique, same kind)
        -- See Note [Extending the TCvSubst]
        --
        -- In that case we don't need to extend the substitution
        -- to map old to new.  But instead we must zap any
        -- current substitution for the variable. For example:
        --      (\x.e) with id_subst = [x |-> e']
        -- Here we must simply zap the substitution for x

    new_var :: Var
new_var | Bool
no_kind_change = InScopeSet -> Var -> Var
uniqAway InScopeSet
in_scope Var
old_var
            | Bool
otherwise = InScopeSet -> Var -> Var
uniqAway InScopeSet
in_scope (Var -> Var) -> Var -> Var
forall a b. (a -> b) -> a -> b
$
                          Var -> Type -> Var
setTyVarKind Var
old_var (TCvSubst -> Type -> Type
subst_fn TCvSubst
subst Type
old_ki)
        -- The uniqAway part makes sure the new variable is not already in scope

-- | Substitute a covar in a binding position, returning an
-- extended subst and a new covar.
-- Use the supplied function to substitute in the kind
substCoVarBndrUsing
  :: (TCvSubst -> Type -> Type)
  -> TCvSubst -> CoVar -> (TCvSubst, CoVar)
substCoVarBndrUsing :: (TCvSubst -> Type -> Type) -> TCvSubst -> Var -> (TCvSubst, Var)
substCoVarBndrUsing TCvSubst -> Type -> Type
subst_fn subst :: TCvSubst
subst@(TCvSubst InScopeSet
in_scope TvSubstEnv
tenv CvSubstEnv
cenv) Var
old_var
  = ASSERT( isCoVar old_var )
    (InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet
in_scope InScopeSet -> Var -> InScopeSet
`extendInScopeSet` Var
new_var) TvSubstEnv
tenv CvSubstEnv
new_cenv, Var
new_var)
  where
    new_co :: Coercion
new_co         = Var -> Coercion
mkCoVarCo Var
new_var
    no_kind_change :: Bool
no_kind_change = [Type] -> Bool
noFreeVarsOfTypes [Type
t1, Type
t2]
    no_change :: Bool
no_change      = Var
new_var Var -> Var -> Bool
forall a. Eq a => a -> a -> Bool
== Var
old_var Bool -> Bool -> Bool
&& Bool
no_kind_change

    new_cenv :: CvSubstEnv
new_cenv | Bool
no_change = CvSubstEnv -> Var -> CvSubstEnv
forall a. VarEnv a -> Var -> VarEnv a
delVarEnv CvSubstEnv
cenv Var
old_var
             | Bool
otherwise = CvSubstEnv -> Var -> Coercion -> CvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv CvSubstEnv
cenv Var
old_var Coercion
new_co

    new_var :: Var
new_var = InScopeSet -> Var -> Var
uniqAway InScopeSet
in_scope Var
subst_old_var
    subst_old_var :: Var
subst_old_var = Name -> Type -> Var
mkCoVar (Var -> Name
varName Var
old_var) Type
new_var_type

    (Type
_, Type
_, Type
t1, Type
t2, Role
role) = HasDebugCallStack => Var -> (Type, Type, Type, Type, Role)
Var -> (Type, Type, Type, Type, Role)
coVarKindsTypesRole Var
old_var
    t1' :: Type
t1' = TCvSubst -> Type -> Type
subst_fn TCvSubst
subst Type
t1
    t2' :: Type
t2' = TCvSubst -> Type -> Type
subst_fn TCvSubst
subst Type
t2
    new_var_type :: Type
new_var_type = Role -> Type -> Type -> Type
mkCoercionType Role
role Type
t1' Type
t2'
                  -- It's important to do the substitution for coercions,
                  -- because they can have free type variables

cloneTyVarBndr :: TCvSubst -> TyVar -> Unique -> (TCvSubst, TyVar)
cloneTyVarBndr :: TCvSubst -> Var -> Unique -> (TCvSubst, Var)
cloneTyVarBndr subst :: TCvSubst
subst@(TCvSubst InScopeSet
in_scope TvSubstEnv
tv_env CvSubstEnv
cv_env) Var
tv Unique
uniq
  = ASSERT2( isTyVar tv, ppr tv )   -- I think it's only called on TyVars
    (InScopeSet -> TvSubstEnv -> CvSubstEnv -> TCvSubst
TCvSubst (InScopeSet -> Var -> InScopeSet
extendInScopeSet InScopeSet
in_scope Var
tv')
              (TvSubstEnv -> Var -> Type -> TvSubstEnv
forall a. VarEnv a -> Var -> a -> VarEnv a
extendVarEnv TvSubstEnv
tv_env Var
tv (Var -> Type
mkTyVarTy Var
tv')) CvSubstEnv
cv_env, Var
tv')
  where
    old_ki :: Type
old_ki = Var -> Type
tyVarKind Var
tv
    no_kind_change :: Bool
no_kind_change = Type -> Bool
noFreeVarsOfType Type
old_ki -- verify that kind is closed

    tv1 :: Var
tv1 | Bool
no_kind_change = Var
tv
        | Bool
otherwise      = Var -> Type -> Var
setTyVarKind Var
tv (HasCallStack => TCvSubst -> Type -> Type
TCvSubst -> Type -> Type
substTy TCvSubst
subst Type
old_ki)

    tv' :: Var
tv' = Var -> Unique -> Var
setVarUnique Var
tv1 Unique
uniq

cloneTyVarBndrs :: TCvSubst -> [TyVar] -> UniqSupply -> (TCvSubst, [TyVar])
cloneTyVarBndrs :: TCvSubst -> [Var] -> UniqSupply -> (TCvSubst, [Var])
cloneTyVarBndrs TCvSubst
subst []     UniqSupply
_usupply = (TCvSubst
subst, [])
cloneTyVarBndrs TCvSubst
subst (Var
t:[Var]
ts)  UniqSupply
usupply = (TCvSubst
subst'', Var
tvVar -> [Var] -> [Var]
forall a. a -> [a] -> [a]
:[Var]
tvs)
  where
    (Unique
uniq, UniqSupply
usupply') = UniqSupply -> (Unique, UniqSupply)
takeUniqFromSupply UniqSupply
usupply
    (TCvSubst
subst' , Var
tv )   = TCvSubst -> Var -> Unique -> (TCvSubst, Var)
cloneTyVarBndr TCvSubst
subst Var
t Unique
uniq
    (TCvSubst
subst'', [Var]
tvs)   = TCvSubst -> [Var] -> UniqSupply -> (TCvSubst, [Var])
cloneTyVarBndrs TCvSubst
subst' [Var]
ts UniqSupply
usupply'