I’m following this answer to learn how to pattern match on Sequences. For concreteness, imagine that I’m implementing breadth-first search over a 2-d grid using a Sequence as a queue. Using just ViewPatterns, I might come up with something like the following: {-# LANGUAGE ViewPatterns #-} import qualified Data.Sequence as Seq import qualified Data.Set as… Read More Why does using PatternSynonyms trigger a non-exhaustive match warning?