On 6/21/07, Jules Bean
I would write
primary = PrimaryIdentifier `fmap` identifer <|> PrimaryLiteral `fmap` stringLiteral
(I prefer fmap to liftM but they are the same for monads). To my mind this fits the general pattern of 'constructor comes before contents'. with is, of course, just fmap with the parameters reversed.
Nice. I only discovered the joys of Data.Monad, fmap included relatively recently, well after I'd spent quite some time writing parsec parsers. I note that it was Parsec that converted me to Haskell from Mercury[*] - I wrote a library of parser combinators for Mercury, but the lambda notation in Mercury is not nearly so clean as Haskell's, so lacking special syntax for monadic code, the results looked horrible. Much faster - Mercury is a strict language, so it's easier to compile into respectable machine code - but horrible to read. cheers, T. [*] Well, that, and the fact that my thesis was about Mercury, which meant that once I was finished, I never wanted to look at Mercury again. ;-) -- Dr Thomas Conway drtomc@gmail.com Silence is the perfectest herald of joy: I were but little happy, if I could say how much.