Lambda-Term parser

gistfile1.hs

varTerm = do
  char <- noneOf ['.', '\\', '(', ')']
  return $ Var char

appTerm = do
  app <- char '(' *> lambdaTerm <* char ')'
  arg <- lambdaTerm
  return $ App app arg

absTerm = do
  var <-  char '\\' *> anyChar <* char '.'
  fun <- lambdaTerm
  return $ Abs var fun

lambdaTerm = do
  term <- try varTerm <|> appTerm <|> absTerm
  return term

expression = do
  term <- lambdaTerm <* char '\n'
  return term