patch applied (testsuite): Add test for type families, discovered by Roman

[Simon Peyton Jones]

Fri Dec 11 04:26:44 PST 2009  simonpj at microsoft.com
  * Add test for type families, discovered by Roman
  Ignore-this: 82ee6c77a2bd741185ae01d94c4eb694
  
  Tests this patch:
  
    Fri Dec 11 12:01:22 GMT 2009  simonpj at microsoft.com
      * Fix two related bugs in u_tys
      
      When we normalise a type family application we must recursively call
      uTys, *not* 'go', because the latter loop is only there to look
      through type synonyms.  This bug made the type checker generate
      ill-typed coercions, which were rejected by Core Lint.
      
      A related bug only affects the size of coercions.  If faced with
        (m a) ~ (F b c)
      where F has arity 1, we want to decompose to 
         m ~ F Int,  a ~ c
      rather than deferring.  The application decomposition was being
      tried last, so we were missing this opportunity.

    A ./tests/ghc-regress/indexed-types/should_compile/Roman1.hs
    M ./tests/ghc-regress/indexed-types/should_compile/all.T +1

View patch online:
http://darcs.haskell.org/testsuite/_darcs/patches/20091211122644-1287e-3e80c1024c771c093332f8eece6c84e841247f3c.gz