[Haskell-cafe] Parsec float

[Bartosz Wójcik]

On Friday 29 May 2009 22:10:51 Bryan O'Sullivan wrote:
> > myFloat = try (symbol "-" >> float >>= return . negate)
> >     <|>  try float
> >     <|>  (integer >>= return . fromIntegral)
>
> Any time you see ">>= return .", something is being missed. Use liftM or
> <$> instead, i.e. "fromIntegral <$> integer" instead of "integer >>= return
> . fromIntegral".

I don't undersdand what is being missed.

liftM f m1              = do { x1 <- m1; return (f x1) }
so 
liftM fromIntegral integer 
will result the same. Is it then not just a convenience?

Bartek