79 lines
1.8 KiB
Rust
79 lines
1.8 KiB
Rust
import option::{some, none};
|
|
|
|
tag list<T> { cons(T, @list<T>); nil; }
|
|
|
|
fn from_vec<@T>(v: [T]) -> list<T> {
|
|
let l = nil::<T>;
|
|
// FIXME: This would be faster and more space efficient if it looped over
|
|
// a reverse vector iterator. Unfortunately generic iterators seem not to
|
|
// work yet.
|
|
|
|
for item: T in vec::reversed(v) { l = cons::<T>(item, @l); }
|
|
ret l;
|
|
}
|
|
|
|
fn foldl<@T, @U>(ls_: list<T>, u: U, f: block(T, U) -> U) -> U {
|
|
let accum: U = u;
|
|
let ls = ls_;
|
|
while true {
|
|
alt ls {
|
|
cons(hd, tl) { accum = f(hd, accum); ls = *tl; }
|
|
nil. { break; }
|
|
}
|
|
}
|
|
ret accum;
|
|
}
|
|
|
|
fn find<@T, @U>(ls_: list<T>, f: block(T) -> option::t<U>) -> option::t<U> {
|
|
let ls = ls_;
|
|
while true {
|
|
alt ls {
|
|
cons(hd, tl) {
|
|
alt f(hd) { none. { ls = *tl; } some(rs) { ret some(rs); } }
|
|
}
|
|
nil. { break; }
|
|
}
|
|
}
|
|
ret none;
|
|
}
|
|
|
|
fn has<@T>(ls_: list<T>, elt: T) -> bool {
|
|
let ls = ls_;
|
|
while true {
|
|
alt ls {
|
|
cons(hd, tl) { if elt == hd { ret true; } else { ls = *tl; } }
|
|
nil. { break; }
|
|
}
|
|
}
|
|
ret false;
|
|
}
|
|
|
|
fn length<@T>(ls: list<T>) -> uint {
|
|
fn count<T>(_t: T, u: uint) -> uint { ret u + 1u; }
|
|
ret foldl(ls, 0u, count);
|
|
}
|
|
|
|
fn cdr<@T>(ls: list<T>) -> list<T> {
|
|
alt ls { cons(_, tl) { ret *tl; } nil. { fail "list empty" } }
|
|
}
|
|
|
|
fn car<@T>(ls: list<T>) -> T {
|
|
alt ls { cons(hd, _) { ret hd; } nil. { fail "list empty" } }
|
|
}
|
|
|
|
fn append<@T>(l: list<T>, m: list<T>) -> list<T> {
|
|
alt l {
|
|
nil. { ret m; }
|
|
cons(x, xs) { let rest = append(*xs, m); ret cons(x, @rest); }
|
|
}
|
|
}
|
|
|
|
// Local Variables:
|
|
// mode: rust;
|
|
// fill-column: 78;
|
|
// indent-tabs-mode: nil
|
|
// c-basic-offset: 4
|
|
// buffer-file-coding-system: utf-8-unix
|
|
// compile-command: "make -k -C $RBUILD 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
|
|
// End:
|