GHC.HsToCore.Pmc.Types

Types used through-out pattern match checking. This module is mostly there to be imported from GHC.HsToCore.Types. The exposed API is that of GHC.HsToCore.Pmc.

These types model the paper Lower Your Guards: A Compositional Pattern-Match Coverage Checker".

LYG syntax

Guard language

newtype SrcInfo

Means by which we identify a source construct for later pretty-printing in a warning message. SDoc for the equation to show, Located for the location.

Constructors

SrcInfo (Located SDoc)

Instances

Outputable SrcInfo

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: SrcInfo -> SDoc

data PmGrd

A very simple language for pattern guards. Let bindings, bang patterns, and matching variables against flat constructor patterns. The LYG guard language.

Constructors

PmCon

PmCon x K dicts args corresponds to a K dicts args <- x guard. The args are bound in this construct, the x is just a use. For the arguments' meaning see ConPatOut.

Fields

• pm_id :: !Id
• pm_con_con :: !PmAltCon
• pm_con_tvs :: ![TyVar]
• pm_con_dicts :: ![EvVar]
• pm_con_args :: ![Id]

PmBang

PmBang x corresponds to a seq x True guard. If the extra SrcInfo is present, the bang guard came from a source bang pattern, in which case we might want to report it as redundant. See Note [Dead bang patterns] in GHC.HsToCore.Pmc.Check.

Fields

• pm_id :: !Id
• _pm_loc :: !(Maybe SrcInfo)

PmLet

PmLet x expr corresponds to a let x = expr guard. This actually binds x.

Fields

• pm_id :: !Id
• _pm_let_expr :: !CoreExpr

Instances

Outputable PmGrd

Should not be user-facing.

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: PmGrd -> SDoc

newtype GrdVec

A sequence of PmGrds.

Constructors

GrdVec [PmGrd]

Instances

Outputable GrdVec

Format LYG guards as | True <- x, let x = 42, !z

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: GrdVec -> SDoc

Guard tree language

newtype PmMatchGroup p

A guard tree denoting MatchGroup.

Constructors

PmMatchGroup (NonEmpty (PmMatch p))

Instances

Outputable p => Outputable (PmMatchGroup p)

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: PmMatchGroup p -> SDoc

data PmMatch p

A guard tree denoting Match: A payload describing the pats and a bunch of GRHS.

Constructors

PmMatch

Fields

• pm_pats :: !p
• pm_grhss :: !(PmGRHSs p)

Instances

Outputable p => Outputable (PmMatch p)

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: PmMatch p -> SDoc

data PmGRHSs p

A guard tree denoting GRHSs: A bunch of PmLet guards for local bindings from the GRHSss where clauses and the actual list of GRHS. See Note [Long-distance information for HsLocalBinds] in GHC.HsToCore.Pmc.Desugar.

Constructors

PmGRHSs

Fields

• pgs_lcls :: !p
• pgs_grhss :: !(NonEmpty (PmGRHS p))

Instances

Outputable p => Outputable (PmGRHSs p)

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: PmGRHSs p -> SDoc

data PmGRHS p

A guard tree denoting GRHS: A payload describing the grds and a SrcInfo useful for printing out in warnings messages.

Constructors

PmGRHS

Fields

• pg_grds :: !p
• pg_rhs :: !SrcInfo

Instances

Outputable p => Outputable (PmGRHS p)

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: PmGRHS p -> SDoc

newtype PmPatBind p

A guard tree denoting a pattern binding.

Constructors

PmPatBind (PmGRHS p)

Instances

Outputable p => Outputable (PmPatBind p)

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: PmPatBind p -> SDoc

newtype PmEmptyCase

A guard tree denoting an -XEmptyCase.

Constructors

PmEmptyCase

Fields

• pe_var :: Id

Instances

Outputable PmEmptyCase

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: PmEmptyCase -> SDoc

data PmRecSel v

Constructors

PmRecSel

Fields

• pr_arg_var :: v
• pr_arg :: CoreExpr
• pr_cons :: [ConLike]

Coverage Checking types

data RedSets

Redundancy sets, used to determine redundancy of RHSs and bang patterns (later digested into a CIRB).

Constructors

RedSets

Fields

• rs_cov :: !Nablas

  The Covered set; the set of values reaching a particular program point.

• rs_div :: !Nablas

  The Diverging set; empty if no match can lead to divergence. If it wasn't empty, we have to turn redundancy warnings into inaccessibility warnings for any subclauses.

• rs_bangs :: !(OrdList (Nablas, SrcInfo))

  If any of the Nablas is empty, the corresponding SrcInfo pin-points a bang pattern in source that is redundant. See Note [Dead bang patterns].

Instances

Outputable RedSets

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: RedSets -> SDoc

data Precision

Constructors

Approximate

Precise

Instances

Outputable Precision

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: Precision -> SDoc

Monoid Precision

Defined in GHC.HsToCore.Pmc.Types

Methods

mempty :: Precision

mappend :: Precision -> Precision -> Precision

mconcat :: [Precision] -> Precision

Semigroup Precision

Defined in GHC.HsToCore.Pmc.Types

Methods

(<>) :: Precision -> Precision -> Precision

sconcat :: NonEmpty Precision -> Precision

stimes :: Integral b => b -> Precision -> Precision

Show Precision

Defined in GHC.HsToCore.Pmc.Types

Methods

showsPrec :: Int -> Precision -> ShowS

show :: Precision -> String

showList :: [Precision] -> ShowS

Eq Precision

Defined in GHC.HsToCore.Pmc.Types

Methods

(==) :: Precision -> Precision -> Bool

(/=) :: Precision -> Precision -> Bool

data CheckResult a

Pattern-match coverage check result

Constructors

CheckResult

Fields

• cr_ret :: !a

  A hole for redundancy info and covered sets.

• cr_uncov :: !Nablas

  The set of uncovered values falling out at the bottom. (for -Wincomplete-patterns, but also important state for the algorithm)

• cr_approx :: !Precision

  A flag saying whether we ran into the maxPmCheckModels limit for the purpose of suggesting to crank it up in the warning message. Writer state.

Instances

Functor CheckResult

Defined in GHC.HsToCore.Pmc.Types

Methods

fmap :: (a -> b) -> CheckResult a -> CheckResult b

(<$) :: a -> CheckResult b -> CheckResult a

Outputable a => Outputable (CheckResult a)

Defined in GHC.HsToCore.Pmc.Types

Methods

ppr :: CheckResult a -> SDoc

Pre and post coverage checking synonyms

type Pre = GrdVec

Used as tree payload pre-checking. The LYG guards to check.

type Post = RedSets

Used as tree payload post-checking. The redundancy info we elaborated.

Normalised refinement types

module GHC.HsToCore.Pmc.Solver.Types