09:08 am, 17 Jun 05
haskell fun
A short snippet of a haskell session.
I like this definition (which I likely borrowed from somewhere):
So this code is basically: n factorial is the nth element in the list of all factorials.
It memoizes itself! (I think?)
I like this definition (which I likely borrowed from somewhere):
let fac n = scanl1 (*) [1..] !! (n-1)
- scanl1 produces a list of repeatedly applying the operation to elements in the list. So
scanl1 (*) [1..n]
provides factorials from 2 to n. scanl1 (*) [1..]
, then, is the infinite list of factorials. (Values are only generated once they're asked for...)- And !! is the "get the nth element" operator.
So this code is basically: n factorial is the nth element in the list of all factorials.
It memoizes itself! (I think?)
(But no doubt there'll be a standard is Memoized trait)