Overall I am all for simplifying this stuff, but the bit where constraints with no variables are not simplified seems quite confusing.   More concretely, using the example from the proposal:

bar :: forall a b. (a ~ Int) => a -> b -> a

Is it the case that `:t bar @Bool` will print

bar :: (Bool ~ Int) => Bool -> b -> Bool

This looks particularly confusing without the explicit `forall`, although it seems questionable either way.

-Iavor



On Thu, Mar 14, 2019 at 7:47 AM Joachim Breitner <mail@joachim-breitner.de> wrote:
Dear Committee,

Richard, in collarboration with Simon PJ, proposes some tweaks to how
foralls are printed by GHC.

In particular, whenever a type variable is printed with an forall, it
is printed with {a} unless it is a specified variable. And there are
tweaks to what :type does with its argument that makes it more useful,
and obviates the need for a separate :type +v.
https://github.com/goldfirere/ghc-proposals/blob/printing-foralls/proposals/0000-printing-foralls.rst

I like that it actually simplifies the UI (by removing :type +v), so I
recommend acceptance.

Cheers,
Joachim
--
Joachim Breitner
  mail@joachim-breitner.de
  http://www.joachim-breitner.de/

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