cryptic error message

ghci_output.log

*Cis194.Hw.SExpr> :r
[2 of 2] Compiling Cis194.Hw.SExpr  ( src/Cis194/Hw/SExpr.hs, interpreted )

src/Cis194/Hw/SExpr.hs:84:38:
    Couldn't match type `SExpr' with `Atom'
    Expected type: [SExpr] -> Atom
      Actual type: [SExpr] -> SExpr
    In the first argument of `pure', namely `(Comb)'
    In the first argument of `(<*>)', namely `pure (Comb)'
    In the second argument of `(<|>)', namely
      `(pure (Comb) <*> (char '(' *> some parseSExpr <* char ')'))'
Failed, modules loaded: Cis194.Hw.AParser.
*Cis194.Hw.AParser>

parsesexpr.hs

parseAtom :: Parser Atom
parseAtom = (pure (N) <*> posInt) <|> (pure (I) <*> ident)

parseSExpr :: Parser SExpr
parseSExpr = spaces *> parse <* spaces
  where parse = parseAtom <|> (pure (Comb) <*> (char '(' *> some parseSExpr <* char ')'))