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Issue 517: Rule application should not introduce new free variables
1 person starred this issue and may be notified of changes. Back to list
Status:  Released
Owner:  ----
Closed:  Jan 2014


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Project Member Reported by ndmitch...@gmail.com, Dec 10, 2011
Given the hint:

warn = map (\v -> (v, x)) y ==> zip y (repeat x)

If you want it to be correct, you really need to add:

   where _ = notIn v x

However, anything that reduces in a way that introduces a new free variable, i.e:

map (\v -> (v, v)) y ==> zip y (repeat v)

Here the left has [y] as the free variables, and the right has [y,v], so it doesn't really make sense, and HLint should not apply it. This feature could be introduced by automatically introducing notIn constraints where necessary.
Aug 27, 2013
Project Member #1 ndmitch...@gmail.com
Done as described, plus I got to remove all notIn hints.
Status: Fixed
Jan 17, 2014
Project Member #2 ndmitch...@gmail.com
Released in 1.8.53
Status: Released
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