# iter-comprehensions
[![rs-graph crate](https://img.shields.io/crates/v/iter-comprehensions.svg)](https://crates.io/crates/iter-comprehensions)
[![iter-comprehensions docs](https://docs.rs/iter-comprehensions/badge.svg)](https://docs.rs/iter-comprehensions)
## Introduction
`iter-comprehensions` provides a few macros implementing iterator and vector
comprehensions for `Rust`.
1. `comprehension!` for generating a sequence of index tuples
2. `map!` for generating a sequence of expressions
3. `vec!` for constructing vectors
4. `sum!` for computing the sum of some values
5. `product!` for computing the product of some values
The macro `comprehension!` can be used to generate a sequence of elements using
generating sequences and conditional filters.
comprehension!(i1 in RANGE1, COND1, ..., ik in RANGEk)
where RANGE* are iterators (in fact, everything implementing `IntoIterator`)
and each COND* is a boolean condition. Each `RANGE` and `COND` term can use
the variables declared in preceeding range expressions.
The macro `map!` adds an additional expression that computes a value
depending on the indices:
map!(i1 in RANGE1, COND1, ..., ik in RANGEk, EXPR)
map!(EXPR; i1 in RANGE1, COND1, ..., ik in RANGEk)
### Example
The expression `{5i + j: i ∈ {0,…,4}, j ∈ {0,…,4}, i < j }` is
equivalent to the following form
use iter_comprehensions::map;
assert_eq!(map!(5*i + j; i in 0..5, j in 0..5, i < j).collect::<Vec<_>>(),
vec![1, 2, 3, 4, 7, 8, 9, 13, 14, 19]);
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);
## Author
Frank Fischer <frank-fischer@shadow-soft.de>
## Installation
Put the requirement `iter-comprehensions = "^1.0.0"` into the `Cargo.toml` of
your project.
## Documentation
See [docs.rs](https://docs.rs/iter-comprehensions).
## Example
## Download
Source code of latest tagged version: [iter-comprehensions-v1.0.0.tar.gz](/tarball/iter-comprehensions-v1.0.0.tar.gz?uuid=v1.0.0)
Source code of trunk: [iter-comprehensions-trunk.tar.gz](/tarball/iter-comprehensions-trunk.tar.gz?name=iter-comprehensions&uuid=trunk)