Erik de Castro Lopo
Henning Thielemann wrote:
http://www.haskell.org/pipermail/libraries/2012-November/018709.html http://www.haskell.org/pipermail/libraries/2012-December/018716.html
Henning,
In the second link above you wrote:
It would be a good opportunity to check how these packages use isLeft and isRight. E.g. if they use them in connection with fromLeft and fromRight then this would be an argument for me to exclude isLeft and isRight as well.
My main usage of isLeft/isRight is in HSpec tests where I write:
value1 `shouldSatisfy' isLeft value2 `shouldSatisfy' isRight
What I don’t like about this is that isLeft strikes me as having too little mnemonic information in it. While there’s an argument that if one uses “(const True ||| const False)” many times in a programme one might usefully name it, the most suitable name surely depends on the programme. What is the /intention/ of isLeft in the above tests, and can you not name it to reflect that? I’ll grant that for some programmes isLeft may be as good a name as can be found, but I doubt it in general. -- Jón Fairbairn Jon.Fairbairn@cl.cam.ac.uk