Misleading (module) name

[cocreature]

While this package claims to only work for integers, the inferred type is (Num a, Ord a) => a -> Bool so it can work with a lot more than just integers.

[stettberger]

Sorry for that. Functionality was only a mistake. Will be broken in a incompatible way in the future.

[ChristopherKing42]

#4 added a type signature

[mauke]

Here's an alternative implementation more in the spirit of the JS original:

import Data.Typeable

is_positive_integer x = cast x > Just (0 :: Integer)

It has several interesting properties, such as not silently returning True for non-integers.

[stettberger]

Perhaps we can make a software product family from it, by using the C Preprocessor. This would foster reusablity and would make the additional behavior configurable.

[charles-cooper]

Agreed. Further operating-system and architecture specific macros would be appropriate to make the implementation most robust.

#if os(linux)
  is_positive_integer = (0 < )
#elif os(solaris)
  is_positive_integer = (0 < )
#elif os(mingw32)
  is_positive_integer = (0 > )
  -- ^ Special case to match WinAPI semantics
#elif arch(arm)
  is_positive_integer = const True
  -- ^ Special case to make phones use fewer instructions
#elif os(darwin)
  is_positive_integer = const (error "No positive integers for you.")
#else
  is_positive_integer = const (error "We're sorry. We don't know how to implement positive integers for your operating system / architecture")
  -- ^ Generic implementation for unknown operating systems
#endif