Changes between Version 8 and Version 9 of FlexibleContexts


Ignore:
Timestamp:
Mar 31, 2006 10:39:43 PM (8 years ago)
Author:
ross@…
Comment:

note on derived instances

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  • FlexibleContexts

    v8 v9  
    5656 * is required by OverlappingInstances 
    5757 
     58In GHC and Hugs, the contexts of derived instances are fully reduced, so the following instance is allowed only if the instance {{{Eq Bar}}} is in scope: 
     59{{{ 
     60data Foo = K Bar deriving Eq 
     61}}} 
     62 
    5863== Pros == 
    5964 * useful with FlexibleInstances 
     
    6166== Cons == 
    6267 * complicated context reduction story 
    63  * deferred error checking 
     68 * deferred error checking (FunctionalDependencies can ameliorate this)