Add Contravariant instance for Eq and test Show instance.#1211

Merged

ceedubs merged 3 commits intotypelevel:masterfrom peterneyens:contravariant-instances

Jul 19, 2016

+52-3

Commits on Jul 17, 2016

Commits on Jul 18, 2016

Adjust Arbitrary and Eq instances of Eq to comments.
peterneyens
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