ekmett/lens — pull request #425 by startling (2014-04-20 22:15:52+00:00)
Title: Fix the type error in C.L.Properties.

This one:
````
Preprocessing test suite 'properties' for lens-4.2...
[1 of 2] Compiling Control.Lens.Properties ( lens-properties/src/Control/Lens/Properties.hs, dist/build/properties/properties-tmp/Control/Lens/Properties.o )

lens-properties/src/Control/Lens/Properties.hs:47:26:
Couldn't match expected type `Gen b0' with actual type `Property'
In a stmt of a 'do' block:
property
$ traverse_compose
l (\ x -> as ++ [x] ++ bs) (\ x -> if t then Just x else Nothing)
In the second argument of `(.&.)', namely
`do { as <- arbitrary;
bs <- arbitrary;
t <- arbitrary;
property
$ traverse_compose
l
(\ x -> as ++ [x] ++ bs)
(\ x -> if t then Just x else Nothing) }'
In the second argument of `(.&.)', namely
`traverse_pureList l
.&.
do { as <- arbitrary;
bs <- arbitrary;
t <- arbitrary;
property
$ traverse_compose
l
(\ x -> as ++ [x] ++ bs)
(\ x -> if t then Just x else Nothing) }'
````