Changes between Version 3 and Version 4 of FlexibleContexts
 Timestamp:
 Dec 13, 2005 12:19:34 AM (10 years ago)
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FlexibleContexts
v3 v4 7 7 8 8 In Haskell 98, 9 * contexts of type signa rures, `newtype` and `data` declarations consist of assertions of the form C v or C (v t1 ... tn), where v is a type variable. Contexts on `newtype` and `data` declarations are RemovalCandidates.9 * contexts of type signatures, `newtype` and `data` declarations consist of assertions of the form C v or C (v t,,1,, ... t,,n,,), where v is a type variable. 10 10 * contexts of `instance` and `class` declarations consist of assertions of the form C v, where v is a type variable. 11 11 The proposal is that class arguments in contexts of type signatures and `class` declarations may be arbitrary types, e.g. … … 13 13 g :: (C [a], D (a > b)) => [a] > b 14 14 }}} 15 (Similar relaxation of `instance` declarations leads to UndecidableInstances.) 15 (Similar relaxation of `instance` declarations leads to UndecidableInstances. 16 Contexts on `newtype` and `data` declarations are RemovalCandidates.) 16 17 17 18 == References == … … 55 56 56 57 == Cons == 57 * Complicated context reduction story58 * Deferred error checking58 * complicated context reduction story 59 * deferred error checking