Safe Haskell	Safe
Language	Haskell98

SMR.Core.Step

Synopsis

data Config s p w = Config {
- configUnderLambdas :: !Bool
- configHeadArgs :: !Bool
- configPrims :: !(Map p (PrimEval s p w))
- configDeclsMac :: !(Map Name (Exp s p))
}
data World w = World {
- worldNomGen :: !(IORef Integer)
- worldUser :: w
}
data Result
- = ResultDone
- | ResultError Text
newWorld :: w -> IO (World w)
steps :: (Ord p, Show p) => Config s p w -> World w -> Exp s p -> IO (Either Text (Exp s p))
step :: (Ord p, Show p) => Config s p w -> World w -> Exp s p -> IO (Either Result (Exp s p))

Documentation

data Config s p w Source #

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 Source #

World state for evaluation

Constructors

World
Fields worldNomGen :: !(IORef Integer) Generator for nominal variables. worldUser :: w User state

data Result Source #

Result of evaluation.

Constructors

ResultDone
ResultError Text

Instances

Show Result Source #
Instance details Defined in SMR.Core.Step Methods showsPrec :: Int -> Result -> ShowS # show :: Result -> String # showList :: [Result] -> ShowS #

newWorld :: w -> IO (World w) Source #

Initialize a new world.

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

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)) Source #

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.