summaryrefslogtreecommitdiff
path: root/revtwice.icl
blob: e5186d4f9dce1b81bd5272d6f9e804d14e3259a3 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
module revtwice

/*
Reversing a list a number of times using Twice.

Increase stack size to 1m and heap size to 2m to run this program.

A list containing 25 integers is reversed 65536 times by means
of four applications of the higher order function Twice.
*/

import StdInt, StdEnum

Revv:: [Int] -> [Int]
Revv l  =  Rev l []
where
	Rev::[Int] [Int] -> [Int]
	Rev [x:r] list	=  Rev r [x : list]
	Rev []    list	=  list

Twice::(x -> x) x -> x
Twice f x =  f (f x)

Start::[Int]
Start = Twice Twice Twice Twice Revv [1..25]