Re: [Haskell-cafe] instance Eq (a -> b)

On 14 April 2010 16:03, Ashley Yakeley wrote:

Why isn't there an instance Eq (a -> b) ?

How do you prove that f = (2*) and g x = x + x are equal? Mathematically, you can; but the only way you can "prove" it in Haskell is by comparing the values for the entire domain (which gets computationally expensive)... Or, how about higher order functions like map? -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com IvanMiljenovic.wordpress.com