[−][src]Crate iter_comprehensions

Compact iterator and vector comprehensions.

This crate implements a few macros with generating comprehension expressions.

iter! for an iterator
vec! for constructing vectors
sum! for computing the sum of some values
product! for computing the product of some values

The macro iter! can be used to generate a sequence of elements using generating sequences and conditional filters.

iter!(EXPR; VAR in RANGE, COND, ...)

where EXPR the generator expression, VAR is a variable RANGE a some sequence, e.g. 0..n (in fact, everything implementing IntoIterator). COND is an arbitrary boolean expression. Each RANGE and COND term can use the variables declared in preceeding range expressions.

Example

The expression $\{ 5i + j : i \in \{0..4\}, j \in \{0..4\}, i < j \}$ is equivalent to the following form

use iter_comprehensions::iter;
assert_eq!(iter!(4*i + j; i in 0..5, j in 0..5, i < j).collect::<Vec<_>>(),
           vec![1, 2, 3, 4, 6, 7, 8, 11, 12, 16]);

The analogous syntax can be used to create vectors:

use iter_comprehensions::vec;
assert_eq!(vec![i; i in 0..5], vec![0,1,2,3,4]);
assert_eq!(vec![(i,j); i in 0..3, j in 0..3, i < j],
           vec![(0,1), (0,2), (1,2)]);

Computing a sum of values:

use iter_comprehensions::{sum, vec};
assert_eq!(sum!(i; i in 1..10, i % 2 == 1), 25);
let S = vec![i; i in 1..10];
assert_eq!(sum!(i in S, i % 2 == 1, i), 25);

Computing a product of values:

use iter_comprehensions::product;
assert_eq!(product!(i; i in 1..=5), 120);
assert_eq!(product!(i in 1..=5, i), 120);

Macros

iter	An iterator comprehension.
product	A product expression.
sum	A sum expression.
vec	Extension of `vec!` with comprehensions.

Functions

productiter
sumiter