Could tester2 return "some kind of base type", which the two inherit from? I don't know. I'm really only presenting the ugly tester2 function because I'm looking for a Parsec-concordant solution to what appears a simple problem. What I'd like is to parse either the string "parameter", or the string ":". I'm using 'reserved' and 'symbol' because they seem to correspond well to the concepts in the language I'm parsing. I could try, tester3 = reserved "parameter" <|> do { symbol ":"; return () } but that's feels a bit contrived; or I could use 'reserved' twice. Perhaps I'd express my confusion better if I ask: Why are 'reserved' and 'symbol' different types? Paul (Haskell Novice) -----Original Message----- From: Jonathan Cast [mailto:jonathanccast@fastmail.fm] Sent: Fri 3/28/2008 2:05 PM To: Paul Keir Cc: Luke Palmer; haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Parsec Expected Type On 28 Mar 2008, at 2:02 AM, Paul Keir wrote:
Thanks, I'd thought it was something to do with incompatible types. I can now create a simpler problem:
tester2 = reserved "parameter" <|> symbol ":"
Certainly I could use reserved ":" instead of symbol, but where is my thinking with symbol here going wrong? Surely the above example isn't so odd?
What type do you expect tester2 to return? jcc