SMR.Core.Step

Documentation

data Config s p w

Evaluation config

Constructors

Config

Fields

• configUnderLambdas :: !Bool

  Reduce under lambda abstractions.

• configHeadArgs :: !Bool

  Reduce arguments when head is not an abstraction.

• configPrims :: !(Map p (PrimEval s p w))

  Primitive operator declarations.

• configDeclsMac :: !(Map Name (Exp s p))

  Macro declarations.

data World w

World state for evaluation

Constructors

World

Fields

• worldNomGen :: !(IORef Integer)

  Generator for nominal variables.

• worldUser :: w

  User state

data Result

Result of evaluation.

Constructors

ResultDone

ResultError Text

Instances

Show Result

Methods

showsPrec :: Int -> Result -> ShowS

show :: Result -> String

showList :: [Result] -> ShowS

newWorld :: w -> IO (World w)

Initialize a new world.

steps :: (Ord p, Show p) => Config s p w -> World w -> Exp s p -> IO (Either Text (Exp s p))

Multi-step reduction to normal form.

step :: (Ord p, Show p) => Config s p w -> World w -> Exp s p -> IO (Either Result (Exp s p))

Single step reduction.

This is a definitional interpreter, intended to be easy to understand and get right, but not fast. Each time we take a step we decend into the AST looking for the next redex, which causes evaluation to have a higher asymptotic complexity than it would with an evaluator that that manages the evaluation context properly.