kind inference

Simon Peyton-Jones simonpj at microsoft.com
Thu Nov 17 07:32:37 EST 2005


Yes it's deliberate.  (Turned out to be easy and convenient.)   Yes it
goes beyond H98, so GHC types a few too many programs even in H98 mode.
I guess I should document it.

Simon

| -----Original Message-----
| From: glasgow-haskell-users-bounces at haskell.org
[mailto:glasgow-haskell-users-
| bounces at haskell.org] On Behalf Of Ross Paterson
| Sent: 17 November 2005 11:31
| To: glasgow-haskell-users at haskell.org
| Subject: kind inference
| 
| The Haskell 98 Report says kind inference is to be done over
dependency
| groups with polymorphic kinds defaulted to *, and hence the following
| example (from 4.6) is illegal:
| 
| 	data Tree a  = Leaf | Fork (Tree a) (Tree a)
| 
| 	type TreeList = Tree []
| 
| GHC 6.4 seems to perform kind inference across all the data, newtype,
| type and class declarations of a module before defaulting, and so
accepts
| the above.  An improvement, I think, but unadvertised.  Was it
intentional?
| 
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