An IsString (NonEmpty Char) instance

Merijn Verstraaten merijn at
Wed Sep 13 09:49:52 UTC 2017

> On 4 Sep 2017, at 0:25, Ivan Lazar Miljenovic <ivan.miljenovic at> wrote:
> Sorry, yes, I was thinking that GHC could determine that the result
> was Nothing and throw a type-checking failure, but that doesn't work.

So, I proposed something like this a year or more ago and got shot down because people wanted a proof-of-concept to prove it usefulness first. I implemented a very rough one that I've been thinking about polishing to the point of actually being useful (Especially now that we can *finally* derive Lift instance for other datatypes). Comments/feedback welcome, but I'm not sure how soon I can get back to this.


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