module SExpr where

import           AParser
import           Control.Applicative
import           Data.Char

zeroOrMore :: Parser a -> Parser [a]
zeroOrMore p = oneOrMore p <|> pure []

oneOrMore :: Parser a -> Parser [a]
oneOrMore p = (:) <$> p <*> zeroOrMore p

spaces :: Parser String
spaces = zeroOrMore $ satisfy isSpace

ident :: Parser String
ident = (:) <$> satisfy isAlpha <*> zeroOrMore (satisfy isAlphaNum)

-------------------- when evaluated i the results well -------------------------
-- >>> runParser ident "foobar baz"
-- Just ("foobar"," baz")
-- >>> runParser ident "foo33fA"
-- Just ("foo33fA","")
-- >>> runParser ident "2bad"
-- Nothing
-- >>> runParser ident ""
-- Nothing


-------------------- when evaluated sometimes i get them with these exceptions -------------------------

-- >>> runParser ident "foobar baz"
-- <interactive>:338:2-10: error:
--     Variable not in scope:
--       runParser :: AParser.Parser String -> [Char] -> t
-- >>> runParser ident "foo33fA"
-- <interactive>:339:2-10: error:
--     Variable not in scope:
--       runParser :: AParser.Parser String -> [Char] -> t
-- >>> runParser ident "2bad"
-- <interactive>:340:2-10: error:
--     Variable not in scope:
--       runParser :: AParser.Parser String -> [Char] -> t
-- >>> runParser ident ""
-- <interactive>:341:2-10: error:
--     Variable not in scope:
--       runParser :: AParser.Parser String -> [Char] -> t