[Haskell-cafe] Where does ~> come from?

[David Menendez]

On Feb 19, 2008 4:15 PM, Wolfgang Jeltsch <g9ks157k at acme.softbase.org> wrote:
> Am Dienstag, 19. Februar 2008 18:26 schrieben Sie:
> > […]
>
> > However, I was told this:  ~> a b is a ~> b, but if I write c a b and
> > wish the effect of a `c` b. This would not work. ~> as an infix operator
> > has a special place in GHC. It is not "just a type variable".
>
> Sorry, but I don't understand fully what you mean. :-(  But nevertheless,
> a ~> b is not the same as ~> a b but as (~>) a b.  It's just like with
> ordinary operators where a + b is the same as (+) a b.

Note that some (all?) versions of GHC will incorrectly print "a ~> b"
as "~> a b".

<http://hackage.haskell.org/trac/ghc/ticket/1930>

Prelude> :t undefined :: a + b
undefined :: a + b :: forall (+ :: * -> * -> *) a b. + a b

It mostly gets infix type constructors right, although there are
apparently problems with precedence and associativity.

-- 
Dave Menendez <dave at zednenem.com>
<http://www.eyrie.org/~zednenem/>