New type of ($) operator in GHC 8.0 is problematic

Ben Gamari ben at
Tue Feb 16 11:02:51 UTC 2016

Christopher Allen <cma at> writes:

> I don't think it's a good idea to create a dumbed down Prelude and existing
> resources not covering what programmers need to know in order to actually
> use Haskell as everyone else uses it is much of the reason I had to write a
> book to begin with. This type isn't just noise for beginners, it's noise
> for practitioners too. Consider what I said earlier about a 15 year user of
> Haskell finding the type confusing and irrelevant.

I agree that until we have shown that these polymorphic uses offer real
value in common use-cases we shouldn't allow them to add noise to our
common combinator types.

> There are a couple good proposals for addressing levity polymorphism
> leaking into the type. I think the one Ben Gamari had in mind that I
> thought would be fine is waiting for a patch.
I believe this is on Richard's todo list.


- Ben
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 472 bytes
Desc: not available
URL: <>

More information about the ghc-devs mailing list