#9548: Numerical type system problem -------------------------------------+------------------------------------- Reporter: vxanica | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: libraries/base | Version: 7.8.3 Keywords: Number | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Originally, in haskell 98 the factorial function {{{#!hs f 0 = 1 f n = n * f (n - 1) }}} has type Num a => a -> a, while after ghc 7.4 it requires Eq type class. I suggest that Num type class should be redefined as {{{#!hs class Eq a => Num a where ... }}} Since all the numbers are equality checkable. we can be more aggressive to have Order super class for numbers even complex numbers are not well ordered. I suppose that this is like the historical problem like Applicative should be the super class of Monad. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9548 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler