<div dir="ltr">This is already a separate extension: PatternSignatures. However, that extension is deprecated for some reason.<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Aug 6, 2013 at 2:46 PM, Evan Laforge <span dir="ltr"><<a href="mailto:qdunkan@gmail.com" target="_blank">qdunkan@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Occasionally I have to explicitly add a type annotation, either for<br>
clarity or to help choose a typeclass instance. Usually top-level<br>
type annotations take care of this, but sometimes it's convenient to<br>
only annotate a certain value, e.g. one argument of a lambda.<br>
<br>
I've noticed that while vanilla haskell is happy to allow me to put<br>
type annotations on variables where they are used (e.g. '\x -> f (x ::<br>
T)'), if I put it on the variable where it is bound (e.g. '\(x :: T)<br>
-> f x'), it wants me to turn on ScopedTypeVariables.<br>
<br>
I think ScopedTypeVariables is a nice extension and I'm sure it comes<br>
from a perfectly respectable family and all, but it feels like<br>
annotations on arguments comes in as a side-effect.<br>
<br>
Would it make sense to split it into a separate extension like<br>
TypesOnArguments so I can more accurately express my deviation from<br>
haskell2010 orthodoxy? Or is there some deeper tie between scoped<br>
type variables and annotations on arguments?<br>
<br>
Now that I think of it, it seems inconsistent that 'x :: A -> B; x a =<br>
...' is valid, but 'x = \(a :: A) -> (...) :: B' is not. Doesn't the<br>
former desugar to the latter?<br>
<br>
And what about getting ScopedTypeVariables into haskell prime? As far<br>
as I know everyone loves it, or at least no one actually hates it :)<br>
<br>
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</blockquote></div><br></div>