oleg-7 wrote:
In fact, that distinction is possible. The following article
How to write an instance for not-a-function http://okmij.org/ftp/Haskell/typecast.html#is-function-type
specifically describes a method of writing an instance which is selected only when the type in question is NOT a function. The method is quite general and has been extensively used (for example, to implement deep monadic join).
That's really incredible, and yet I don't quite understand how IsFunction works. Here is my very short but powerful solution (nary is renamed to wrap). http://www.nabble.com/file/p14220591/wrap.hs wrap.hs -- View this message in context: http://www.nabble.com/distinguish-functions-from-non-functions-in-a-class-in... Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.