There's no hidden/default parameters in haskell (records have default values but that's different), that line is eta reduced because those 2 functions always be

There's no hidden/default parameters in haskell (records have default values but that's different), that line is eta reduced because those 2 functions always behave identically number = return You have to figure what you did in that GHCi session that defined (return) to shadow the Prelude one that everybody knows about, which is the only one in language and "standard libs" with that name http://www.haskell.org/hoogle/?hoogle=return http://www.haskell.org/hoogle/?hoogle=return I am confident you'd get good answers somewhere where people are monitoring for hsakell questions (SO, reddit, mailing list; on HN threads usually disappear in a few hours)(tikhonj's answers are excellent, but s/he is only one person): https://plus.google.com/100165496075034135269/posts/UztvNpAJfow https://plus.google.com/100165496075034135269/posts/UztvNpAJ...