[darcs-users] darcs patch: couple of GADT build fixes for recent GHCs
Jason Dagit
dagit at codersbase.com
Sun Aug 30 18:46:32 UTC 2009
On Sun, Aug 30, 2009 at 5:33 AM, Ganesh Sittampalam<ganesh at earth.li> wrote:
> Mon Aug 3 06:05:14 BST 2009 Ganesh Sittampalam <ganesh at earth.li>
> * couple of GADT build fixes for recent GHCs
This is dealing with the typical issue of using existential types in a
polymorphic pattern match. In particular,
- let Sealed ps = flattenOne t
Causes GHC's head to explode. The reason is that let and where are
not-monomorphic like "case", lambda, and function definitions. This
makes existentials very hard to reason about. GHC tackles it by
giving up (perhaps the only reasonable solution).
The refactorings look fine to me.
Jason
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