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//! The examples from the ICFP submission, all in one place.
// 2.1
pub fn ref_incr(x: &mut i32) {
*x = *x + 1;
}
pub fn test_incr() {
let mut x = 0i32;
ref_incr(&mut x);
assert!(x == 1);
}
// 2.2
pub fn choose<'a, T>(b: bool, x: &'a mut T, y: &'a mut T) -> &'a mut T {
if b {
return x;
} else {
return y;
}
}
pub fn test_choose() {
let mut x = 0;
let mut y = 0;
let z = choose(true, &mut x, &mut y);
*z = *z + 1;
assert!(*z == 1);
assert!(x == 1);
assert!(y == 0);
}
// 2.3
pub enum List<T> {
Cons(T, Box<List<T>>),
Nil,
}
use List::Cons;
use List::Nil;
pub fn list_nth_mut<'a, T>(l: &'a mut List<T>, i: u32) -> &'a mut T {
match l {
Nil => {
panic!()
}
Cons(x, tl) => {
if i == 0 {
return x;
} else {
return list_nth_mut(tl, i - 1);
}
}
}
}
pub fn sum(l: &List<i32>) -> i32 {
match l {
Nil => {
return 0;
}
Cons(x, tl) => {
return *x + sum(tl);
}
}
}
pub fn test_nth() {
let mut l = Cons(1, Box::new(Cons(2, Box::new(Cons(3, Box::new(Nil))))));
let x = list_nth_mut(&mut l, 2);
*x = *x + 1;
assert!(sum(&l) == 7);
}
// 4.3
pub fn call_choose(mut p: (u32, u32)) -> u32 {
let px = &mut p.0;
let py = &mut p.1;
let pz = choose(true, px, py);
*pz = *pz + 1;
return p.0;
}
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