Iterator comprehension in Rust
The syntax is derived from Haskell's list comprehension. This library use iterators instead of lists.
// this returns the iterator generates `[0, 1, 4, ..., 81]`
iter![x * x; x <- 0..10];You can also use patterns in generators,
iter![x * y; (x, y) <- vec![(1, 1), (2, 3), (4, 5)]];
// => [1, 6, 20]filtering values,
iter![(i, j); i <- 1.., j <- 1..i, gcd(i, j) == 1].take(10)
// => [(1, 1), (2, 1), (2, 2), (2, 3), (2, 4), (3, 1), (3, 2), (3, 3), (3, 4), (3, 5)]and let bindings.
iter![(i, j); i <- 1.., let k = i * i, j <- 1..=k].take(10);
// => [(1, 1), (2, 1), (2, 2), (2, 3), (2, 4), (3, 1), (3, 2), (3, 3), (3, 4), (3, 5)]Some useful variants are provided.
vect! returns Vec:
// just same as iter![].collect::<Vec<_>>()
vect![x * x; x <- 0..10];sum! return sum of iterator:
let t = sum![x; x <- 1..=10]; // => 55
// same as this:
// let t = iter![x; x <- 1..=10].sum()
// but this does not compiles (need type annotation).
let t = iter![x; x <- 1..=10].sum::<i32>()
// `sum!` can infer the return type, so it has non-trivial functionality.Also has product! macro:
let t = product![x; x <- 1..=10]; // => 3628800