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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Yes I suspect that patSynSig should return three results: the quantified tyvars, the lhs types and the rhs type<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Dr. ÉRDI Gergõ [mailto:gergo@erdi.hu]
<br>
<b>Sent:</b> 20 August 2013 03:09<br>
<b>To:</b> Simon Peyton-Jones<br>
<b>Cc:</b> ghc-devs@haskell.org<br>
<b>Subject:</b> RE: Instantiating a type with fresh, flexi type variables<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Hi Simon,<o:p></o:p></p>
<p>Here's what I wrote earlier about this to someone who contacted me in private (name withheld because I don't know why he contacted me off-list):<o:p></o:p></p>
<p>"""<br>
So the code in question is this:<br>
<a href="https://github.com/gergoerdi/ghc/commit/f874f8#L5R749">https://github.com/gergoerdi/ghc/commit/f874f8#L5R749</a><o:p></o:p></p>
<p>and the part that feels fishy to me is tcInstTypes, both the implementation and the fact that I have to take care of this manually. I guess the right solution would involve doing something differently in<br>
<a href="https://github.com/gergoerdi/ghc/commit/244b9#L3R43">https://github.com/gergoerdi/ghc/commit/244b9#L3R43</a><br>
so that the types in "rhs_ty" and "args" are correctly generalized. But I haven't been able to find out how that would be done.<br>
"""<o:p></o:p></p>
<p>I'm replying to your other questions in a separate, private mail.<o:p></o:p></p>
<p>Thanks,<br>
Gergo<o:p></o:p></p>
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<p class="MsoNormal">On Aug 20, 2013 6:14 AM, "Simon Peyton-Jones" <<a href="mailto:simonpj@microsoft.com">simonpj@microsoft.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">I'm a bit puzzled that you don't have a *quantified* type, something like<br>
forall abc. ty1 -> ... -> tyn -> ty<br>
to instantiate. I'm a bit suspicious about instantiating all the random free variables of a type (or types). We should talk now I'm back in circulation. What time zone are you in? What's your skype id? (Mine is simonpj0)<br>
<br>
simon<br>
<br>
| -----Original Message-----<br>
| From: ghc-devs [mailto:<a href="mailto:ghc-devs-bounces@haskell.org">ghc-devs-bounces@haskell.org</a>] On Behalf Of Dr. ERDI<br>
| Gergo<br>
| Sent: 08 August 2013 18:37<br>
| To: <a href="mailto:ghc-devs@haskell.org">ghc-devs@haskell.org</a><br>
| Subject: Instantiating a type with fresh, flexi type variables<br>
|<br>
| For my pattern-synonyms branch (see prev. email) I had to write the<br>
| following function, incl. making TcValidity.fvTypes public:<br>
|<br>
| tcInstTypes :: [TcType] -> TcM [TcType]<br>
| tcInstTypes tys<br>
| = do { let tvs = fvTypes tys<br>
| ; (_, _, subst) <- tcInstTyVars tvs<br>
| ; return $ map (substTy subst) tys }<br>
|<br>
| I'm surprised I had to write this myself, and this made me wonder if<br>
| there's a much better way to handle cases where I have some kind of<br>
| definition which has some inferred type, and then various use sites<br>
| of that definition must all have types that can be unified with this<br>
| original inferred type.<br>
| Is there?<br>
|<br>
| Thanks,<br>
| Gergo<br>
|<br>
| _______________________________________________<br>
| ghc-devs mailing list<br>
| <a href="mailto:ghc-devs@haskell.org">ghc-devs@haskell.org</a><br>
| <a href="http://www.haskell.org/mailman/listinfo/ghc-devs" target="_blank">http://www.haskell.org/mailman/listinfo/ghc-devs</a><o:p></o:p></p>
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