Marcin 'Qrczak' Kowalczyk wrote:
Bulat Ziganshin <[EMAIL PROTECTED]> writes:
that i want to say is what the first variant allows to define type of
'x' in such way that the only Show-specific operations are allowed,
Why?
Parametricity, what else? I'd much rather pass my precious String to a
function of type [a] -> [a] or Functor a => a Char -> a Char than to a
function of type String -> String. Restricting an interface is a very good
thing from a program verification standpoint. It's much the same in
object-oriented languages, except that the existence of dynamic downcasting
kind of spoils things. But then, Haskell has undefined and unsafePerformIO.
-- Ben
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