<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Mar 14, 2019, at 6:18 PM, Iavor Diatchki <<a href="mailto:iavor.diatchki@gmail.com" class="">iavor.diatchki@gmail.com</a>> wrote:</div><div class=""><div dir="ltr" style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><div dir="ltr" class=""><div dir="ltr" class=""><br class=""></div><div dir="ltr" class="">bar :: forall a b. (a ~ Int) => a -> b -> a<br class=""></div><div dir="ltr" class=""><br class=""></div><div class="">Is it the case that `:t bar @Bool` will print</div><div class=""><br class=""></div><div class="">bar :: (Bool ~ Int) => Bool -> b -> Bool<br class=""></div><div class=""><br class=""></div><div class="">This looks particularly confusing without the explicit `forall`, although it seems questionable either way.</div></div></div></div></blockquote><div><br class=""></div><div>Yes, you understand correctly. `:t bar @Bool` will print that unfortunate type. I agree this is questionable. But I don't know how to do better. The current state of affairs is awkward in a different way, in that `:t bar @Bool` errors (that's OK) and `:t bar @Int` prints `forall {b}. Int -> b -> Int`, even though a further visible type application is possible. Perhaps worse, `:t bar` today prints `forall {b}. Int -> b -> Int` even though the next variable to be instantiated is `a`. This is why we have `:type +v`.</div><div><br class=""></div><div>The direction in the proposal came about in wondering if it's possible to improve the mechanics of `:t` (without the `+v`). After we thought of doing maximal instantiation of inferred arguments (but no generalization), then we realized we could drop `:type +v` as redundant. I agree it's something of an uneasy compromise here, but I think any choice is going to have unfortunate behavior in some scenarios.</div><div><br class=""></div><div>Richard</div><br class=""><blockquote type="cite" class=""><div class=""><div dir="ltr" style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><div dir="ltr" class=""><div class=""><br class=""></div><div class="">-Iavor</div><div class=""><br class=""></div><div class=""><br class=""></div></div></div><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><div class="gmail_quote" style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;"><div dir="ltr" class="gmail_attr">On Thu, Mar 14, 2019 at 7:47 AM Joachim Breitner <<a href="mailto:mail@joachim-breitner.de" class="">mail@joachim-breitner.de</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-style: solid; border-left-color: rgb(204, 204, 204); padding-left: 1ex;">Dear Committee,<br class=""><br class="">Richard, in collarboration with Simon PJ, proposes some tweaks to how<br class="">foralls are printed by GHC.<br class=""><br class="">In particular, whenever a type variable is printed with an forall, it<br class="">is printed with {a} unless it is a specified variable. And there are<br class="">tweaks to what :type does with its argument that makes it more useful,<br class="">and obviates the need for a separate :type +v.<br class=""><a href="https://github.com/goldfirere/ghc-proposals/blob/printing-foralls/proposals/0000-printing-foralls.rst" rel="noreferrer" target="_blank" class="">https://github.com/goldfirere/ghc-proposals/blob/printing-foralls/proposals/0000-printing-foralls.rst</a><br class=""><br class="">I like that it actually simplifies the UI (by removing :type +v), so I<br class="">recommend acceptance.<br class=""><br class="">Cheers,<br class="">Joachim<br class="">--<span class="Apple-converted-space"> </span><br class="">Joachim Breitner<br class=""> <span class="Apple-converted-space"> </span><a href="mailto:mail@joachim-breitner.de" target="_blank" class="">mail@joachim-breitner.de</a><br class=""> <span class="Apple-converted-space"> </span><a href="http://www.joachim-breitner.de/" rel="noreferrer" target="_blank" class="">http://www.joachim-breitner.de/</a><br class=""><br class="">-----BEGIN PGP SIGNATURE-----<br class=""><br class="">iQIzBAABCAAdFiEEGkYIf5Vdk8V8YFcbPZCKs/D79R8FAlyKaX8ACgkQPZCKs/D7<br class="">9R/7oxAAgU213SuV+1lr/JExnMSPNWD6s7CPTWdauLK+tHYUv1MD3HeZlBZb2pvN<br class="">R/swC6jdm95vKXWeMVhfYGFGepOdMEKzqBWLDf3fCO29MlHlb4barwtEZOZ9AbaM<br class="">DSyE+RjVQ35ATZPvfFTYdBacBrvCivoRWcUdi10ps6rizI86gKeCiG1PN5nVMNV+<br class="">cpvTpFWRm/xmbtU4xFWuZ9FjL0bfO6yJCueX07gTkdZYW4vnvWSdis6CInkQZ7SA<br class="">hXbTEYNT9zMCGvJMG+NQN+5c0h3GJlUoTsNGd0PsQnkvoYiLjM52eM5hzkz5zFRr<br class="">mMYT381T1nnIl505IFGuT/je5KAn7wTImIXvvclwDxfjCBn3J1IRVAbikgwlTU4M<br class="">9L+tlQiTKI8OZpbgpPjjRj4hWrnX1gzWiIGwtPYtQuPhkDhEvq0xex8qEKpd7waE<br class="">r5klTYyZrC0LGaHyX5G5yunGLWqnlLKOHAPI20Z1bxVPtDJZ/4g6AoCYSNqBLsHt<br class="">fMTFflHdKTlsCOETPGhaxgf6PP0WvZtNdgTrB2rL5jzKJSOKc1rVRFAdYIr5PP3H<br class="">c4aZGce/ChyFazHeF7hH5UZ7yyB0gMc3T+do6I8vySp0YGeRweb36FU13CduMS05<br class="">rvzb6GIkNFz/Fx2MascE9kZtGvDT9BlxGXqJ9rL/huXquIwN6Gg=<br class="">=1qbg<br class="">-----END PGP SIGNATURE-----<br class="">_______________________________________________<br class="">ghc-steering-committee mailing list<br class=""><a href="mailto:ghc-steering-committee@haskell.org" target="_blank" class="">ghc-steering-committee@haskell.org</a><br class=""><a href="https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee" rel="noreferrer" target="_blank" class="">https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee</a><br class=""></blockquote></div><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">_______________________________________________</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><span style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none; float: none; display: inline !important;" class="">ghc-steering-committee mailing list</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><a href="mailto:ghc-steering-committee@haskell.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">ghc-steering-committee@haskell.org</a><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;" class=""><a href="https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">https://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-steering-committee</a></div></blockquote></div><br class=""></body></html>