In the docs for GHC 7.6.3, e.g. at [1], it is said that one can use LiberalTypeSynonyms as so: `type Discard a = forall b. Show b => a -> b -> (a, String)` This is, however, not possible without RankNTypes which is stated in a tutorial at FPComplete [2] and, of course, GHC 7.6.3 itself says so when trying to compile something with the above definition for Discard: ` Illegal polymorphic or qualified type: forall b. Show b => a -> b -> (a, String) Perhaps you intended to use -XRankNTypes or -XRank2Types In the type declaration for `Discard' ` Maybe the GHC User Guide should be updated to reflect this? /Fredrik References: [1] http://www.bugthunk.net/ghc/docs/7.6.3/html/users_guide_repl/data-type-exten... [2] https://www.fpcomplete.com/school/to-infinity-and-beyond/pick-of-the-week/gu...