determining if a int is a power

Wolfgang Jeltsch wolfgang at
Sat Nov 8 15:17:59 EST 2003

Am Samstag, 8. November 2003, 13:13 schrieb Paul Hudak:
> But note that x `seq` x is equivalent to x, even operationally.  To see why
> denotationally, note that if x evaluates to _|_, so does x `seq` x.  And if
> x evaluates to a value v, so does x `seq` x.  To see why operationally,
> consider the two lists:
>    let x = 1+1 in [x `seq` x]
>    let x = 1+1 in [x]
> Using conventional lazy evaluation in both cases, the term "1+1" is not
> evaluated until the head of the list is taken.  In other words, x `seq` x in
> no way hurries the evaluation of x.

Yes, you are right.

>    -Paul


More information about the Haskell-Cafe mailing list