idris-lang/Idris-dev — pull request #1273 by bmsherman (2014-05-31 02:40:30+00:00)
Title: Add new Err constructor to disambiguate the CantResolveAlts constructor.

(Ironic?) I did this to facilitate pretty printing of names when
Idris cannot disambiguate among alternatives.

This was done to address https://github.com/idris-lang/Idris-dev/issues/1267#issuecomment-44655256.