Suggestion regarding (.) and map

Wolfgang Jeltsch g9ks157k at
Thu Apr 24 16:15:45 EDT 2008

Am Mittwoch, 23. April 2008 23:55 schrieb Cale Gibbard:
> […]

> Rename fmap to map

This would be really great!  There is no point in having a map just for lists 
and a general map for functors since the list map is the same as the list 
instance’s functor map.  And identifiers with a single lowercase letter in 
front or after a lowercase word (fmap, foldr, etc.) are not nice, in my 

> (like it was in Haskell 1.4),

It really was this way in Haskell 1.4?  Why was it changed?

> and define (.) as a synonym for it.

I don’t think that this is reasonable.  (.) corresponds to the little circle 
in math which is a composition.  So (.) = (<<<) would be far better.

> Additionally, add the instance:
> instance Functor ((->) e) where
>     map f g x = f (g x)
> (and hopefully the corresponding Monad instance as well)

And hopefully the corresponding Applicative instance as well!  Applicative 
functors are a very nice thing.  (So a big “thank you” to Conor and Ross.)

> […]

Best wishes,

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