Achim Schneider wrote:
[1..] == [1..]
[some discussion about the nontermination of this expression]
The essence of laziness is to do the least work necessary to cause the desired effect, which is to see that the set of natural numbers equals the set of natural numbers, which, axiomatically, is always computable in O(1) by equality by identity.
This would make sense if Haskell had inbuild equality and (==) where part of the formal semantics of Haskell, wich it isn't. (==) is a library function like every other library function. How could the language or a system implementing the language decide wether this or any other library function returns True without actually running it? Haskell is a programming language, not a theorem prover. Tillmann