Hi,
On Tue, Oct 6, 2009 at 2:37 AM, Henning Thielemann
Numeric literals are treated as Integer or Rational, and are then converted with the function fromInteger or fromRational, respectively, to the required type. Whatever fromInteger function is in scope, will be used. If fromInteger is in a class other than Num (in NumericPrelude it is Ring, but it can be also a function that is not a class method), then number literals have a type like: 2 :: MyNumClass a => a
This is only the case if you use GHC's NoImplicitPrelude extension, otherwise the "fromInteger" of the Prelude is used, even if it is not in scope. Here is an example: module A where boolLit :: Integer -> Bool boolLit 0 = False boolLit _ = True {-# LANGUAGE NoImplicitPrelude #-} module Main where import A(boolLit) import Prelude(Integer,Bool,print) fromInteger :: Integer -> Bool fromInteger = boolLit main = print 0 Note that 0 means different things in the different modules! -Iavor