Changes between Version 18 and Version 19 of TypeFunctionsSolving


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Timestamp:
Jul 30, 2008 3:49:18 PM (7 years ago)
Author:
simonpj
Comment:

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  • TypeFunctionsSolving

    v18 v19  
    2626NB: We explicitly permit equalities of the form `x ~ y` and `a ~ b`, where both sides are either flexible or rigid type variables.
    2727
    28 Coercions `co` are either wanteds (represented by a flexible type variable) or givens ''aka'' locals (represented by a type term of kind CO).  In GHC, they are represented by `TcRnTypes.EqInstCo`.   Moreover, `TcTyFuns.RewriteInst` represents normal equalities, emphasising their role as rewrite rules.
     28Coercions `co` are either wanteds (represented by a flexible type variable) or givens ''aka'' locals (represented by a type term of kind CO).  In GHC, they are represented by `TcRnTypes.EqInstCo`.   Moreover, `TcTyFuns.RewriteInst` represents normal equalities, emphasising their role as rewrite rules.  '''SLPJ''' but I hope the difference between wanted and given is explicit (different constructor) not implicit (look at the form of the coercion).
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