{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses, UndecidableInstances #-}
module Grow.Syntax(
  module Data.Syntax,
  growExpr
  ) where

import Algebra
import Algebra.Parser
import Data.Containers
import Data.Syntax
import Data.Char

instance MonadReader a Id where
  ask = pure undefined
  local _ = id

growExpr :: Parser String [SyntaxT Id]
growExpr = free expr `sepBy1` free (single ';')
  where
    decl = (,)<$>symbol<*>(free (single '=') >> free expr)
    free = (many space >> )
    symbol = many1 (satisfy symChar)
      where symChar c = isAlphaNum c || (c`elem`"/+-_~%*!")
    funAp = (atom`sepBy1`spaces) <&> ValList . map pure
    expr = chainr funAp (op <$> free (single ':' >> (atom <* space))) funAp
      where op f a b = ValList [pure f,pure a,pure b]
    atom = between (single '(') (free $ single ')') (free inParen) + list + dictionary + (Text<$>symbol) + dollar
      where dollar = single '$' >> (atom <&> \e -> ValList [pure $ Text "$",pure e])
    inParen = Function . lambdaSum<$>(free abstract`sepBy`free (single '|'))
              <+> expr
    abstract = lambda<$>atom<*>free (several "~>")*>free expr
    
    list = funcall (pure $ Function id).pure.ValList . map pure
           <$>between (single '[') (free $ single ']') (free expr`sepBy`free (single ','))
    dictionary = mkDict<$>between (single '{') (free $ single '}') (free decl`sepBy`free (single ','))
    mkDict = Dictionary . fromList . map (\(s,v) -> (s,pure v))