2 Oct
2003
2 Oct
'03
12:33 p.m.
On Thu, 2 Oct 2003 12:30:54 +0100
Alastair Reid
Observational equivalence.
For monads like list and maybe, this boils down to the normal equality because the standard equality on these types is exactly observational equality.
For monads like IO, you can't define an Eq instance so it comes down to what can the user of the program observe.
OK. But in my examples, the difference is observable only if I do define a "count" or equivalent to show it. Otherwise, c1/c2 (or m1/m2) are indistinguishable.
(There's a little circularity there and I'm ignoring the exception part of parser monads but, hopefully, you get the idea.)
Yes, thanks a lot. Juanma