gistfile1.hs

module Language.Lisk.Parser2 where

------------------------------------------------------------------------------
-- S-expression parser (Lisk tokenizer)
--

import Control.Applicative
import Text.Parsec hiding ((<|>),many,token,optional,spaces)
import Text.Parsec.Combinator hiding (optional)

data Expr = Atom Atom | List [Expr] | Quote Expr | UnQuote Expr | Splice Expr
  deriving Show
  
data Atom = Var String | Cons String
  deriving Show

expr :: Parsec String () Expr
expr = atom <|> list <|> quote <|> try splice <|> unquote where
  list = fmap List $ parens $ sepBy expr spaces1
  spaces1 = space *> many space
  atom =  Atom <$> (var <|> cons)
  var = Var <$> atomStr
  cons = Cons <$> (char '\'' *> atomStr)
  quote = Quote <$> (char '`' *> expr)
  unquote = UnQuote <$> (char ',' *> expr)
  splice = Splice <$> (string ",@" *> expr)
  atomStr = ((:) <$> atomCharFirst <*> many atomChar)
  atomChar = letter <|> digit <|> oneOf "_'"
  atomCharFirst = letter <|> digit <|> oneOf "_"
  parens = between (char '(') (char ')')

------------------------------------------------------------------------------
-- 
--