Using Pattern synonyms in GHC 8.0.
Using Pattern synonyms in GHC 8.0.

Pattern synonyms can be exported without the "pattern" keyword from GHC 8.0.1
https://downloads.haskell.org/~ghc/8.0.1/docs/html/users_guide/glasgow_exts.html#patsyn-impexp

kazu-yamamoto/dns