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|
{-# LANGUAGE OverloadedStrings #-}
module Language.SimpleShell.Parser.Function
( functionP
, functionP0
)
where
import Language.SimpleShell.AST.Expr (Expr)
import Language.SimpleShell.AST.Function (Function(..))
import Language.SimpleShell.AST.Name (FunName, VarName)
import Language.SimpleShell.AST.SimpleType (SimpleType, FunSig, Typed)
import Language.SimpleShell.Parser (Parser, symbol, declareVars)
import Language.SimpleShell.Parser.Expr (strongTermP, strongTermP_)
import Language.SimpleShell.Parser.Name (nameP, keyword)
import Language.SimpleShell.Parser.SimpleType (simpleTypeP, forceType)
import Control.Applicative ((<|>))
import Text.Megaparsec (sepBy)
functionPrefixP :: Parser (SimpleType, FunName, [Typed VarName])
functionPrefixP = do
keyword "function"
t' <- simpleTypeP
fname <- nameP
params <- symbol "(" *> paramP `sepBy` symbol "," <* symbol ")"
symbol "="
return (t', fname, params)
functionP :: Parser Function
functionP = do
(t', fname, params) <- functionPrefixP
let vars = map snd params
body <- forceType t' (bodyP params) <|> fail "Function return type mismatch."
return $ Function fname vars body
-- | First-pass function parser.
functionP0 :: Parser (FunName, FunSig)
functionP0 = do
(t', fname, params) <- functionPrefixP
let ts = map fst params
bodyP_
return (fname, (t', ts))
paramP :: Parser (Typed VarName)
paramP = (,) <$> simpleTypeP <*> nameP
bodyP :: [Typed VarName] -> Parser (Typed Expr)
bodyP params = declareVars params strongTermP
bodyP_ :: Parser ()
bodyP_ = strongTermP_
|
