<div dir="ltr"><span style="font-family:Arial,Helvetica,sans-serif;font-size:12.727272033691406px">You can wind up in perfectly legitimate situations where the name for the type you are working with isn't in scope, but where you can write a combinator that would infer to have that type. I'd hate to lose that. </span><div>
<span style="font-family:Arial,Helvetica,sans-serif;font-size:12.727272033691406px"><br></span></div><div><span style="font-family:Arial,Helvetica,sans-serif;font-size:12.727272033691406px">It is admittedly of marginal utility at first glance, but there are some tricks that actually need it, and it can also arise if a type synonym expands to a type that isn't exported or brought into scope, so trying to push this line of reasoning too far I is possibly not too productive. </span></div>
<div><span style="font-family:Arial,Helvetica,sans-serif;font-size:12.727272033691406px"><br></span></div><div><span style="font-family:Arial,Helvetica,sans-serif;font-size:12.727272033691406px">Parts of lens, constraints and probably a few other packages I maintain would break as hard data points.</span><div style="margin:0px;padding:0px;border:0px;vertical-align:baseline;font-family:Arial,Helvetica,sans-serif;font-size:12.727272033691406px">
<br></div><div style="margin:0px;padding:0px;border:0px;vertical-align:baseline;font-family:Arial,Helvetica,sans-serif;font-size:12.727272033691406px"><span style="margin:0px;padding:0px;border:0px;vertical-align:baseline;font-size:13px">-Edward</span></div>
</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Apr 22, 2014 at 2:44 AM, Simon Peyton Jones <span dir="ltr"><<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="">| Independent of language extensions, what about types and classes whose<br>
| names are not in scope.  Is there an implicit "... if you import all<br>
| the relevant symbols" and the end of the rule?<br>
<br>
</div>Good point.  I'm honestly unsure how far to push this one!  (It'd be relatively easy to check whether they were in scope and complain if not, but ...)<br>
<span class="HOEnZb"><font color="#888888"><br>
Simon<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
| -----Original Message-----<br>
| From: <a href="mailto:haskell-core-libraries@googlegroups.com">haskell-core-libraries@googlegroups.com</a> [mailto:<a href="mailto:haskell-core-">haskell-core-</a><br>
| <a href="mailto:libraries@googlegroups.com">libraries@googlegroups.com</a>] On Behalf Of David Mazieres<br>
| Sent: 22 April 2014 00:41<br>
| To: Simon Peyton Jones; Haskell Libraries (<a href="mailto:libraries@haskell.org">libraries@haskell.org</a>);<br>
| <a href="mailto:core-libraries-committee@haskell.org">core-libraries-committee@haskell.org</a>; GHC users<br>
| Subject: [core libraries] Re: Tightening up on inferred type signatures<br>
|<br>
| Simon Peyton Jones <<a href="mailto:simonpj@microsoft.com">simonpj@microsoft.com</a>> writes:<br>
|<br>
| > GHC generally obeys this rule<br>
| ><br>
| > * If GHC infers a type f::type, then it's OK for you to add a type<br>
| > signature saying exactly that.<br>
|<br>
| Independent of language extensions, what about types and classes whose<br>
| names are not in scope.  Is there an implicit "... if you import all<br>
| the relevant symbols" and the end of the rule?<br>
|<br>
| David<br>
|<br>
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