9 Apr
2013
9 Apr
'13
10:34 a.m.
On 9 Apr 2013, at 14:46, Sturdy, Ian wrote:
As far as the use of Eq goes, Eq is already enshrined in pattern matching by pattern matching against literals.
Not true. Pattern-matching literals explicitly avoids any use of Eq. Demonstration: data Foo = Foo | Bar instance Eq Foo where _ == _ = True isFoo Foo = True isFoo Bar = False main = do print (isFoo Bar) print (Foo==Bar)