... | ... | @@ -194,6 +194,39 @@ Simon's comment: yes, I guess this is a bit confusing. But the same will happen |
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Koen found this: [ http://hackage.haskell.org/trac/ghc/ticket/1369](http://hackage.haskell.org/trac/ghc/ticket/1369)
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### Fourth report
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Ron de Bruijn (rmbruijn@…) reported:
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```wiki
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[set_left_child_leaf, set_right_child_leaf] = map set_gen_child_leaf [l, r]
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```
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Here "l" and "r" are functions that get the left and right child of a tree and
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set_gen_child is a function generalized over the type of child being
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selected.
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The above doesn't work on GHC 6.6.1. I get
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```wiki
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Cannot match a monotype with `forall s
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a
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(chain :: * -> * -> *)
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(m :: * -> *).
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STRef s (Node s a chain) -> m ()'
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```
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The only other sane way to get this working is to unroll the map by hand.
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## Summary
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... | ... | |