pub mod monad;
pub use monad::Monad;
#[macro_export]
macro_rules! monadic {
(let $v:ident = $e:expr ; $($rest:tt)*) => [Some($e).into_iter().flat_map( move |$v| { monadic!($($rest)*)} )];
(guard $pred:expr ; $($rest:tt)*) => [(if $pred {Some(())} else {None}).into_iter().flat_map( move |_| { monadic!($($rest)*)} )];
(_ <- $monad:expr ; $($rest:tt)* ) => [($monad).into_iter().flat_map( move |_| { monadic!($($rest)*)} )];
($v:ident <- $monad:expr ; $($rest:tt)* ) => [($monad).into_iter().flat_map( move |$v| { monadic!($($rest)*)} )];
($monad:expr ) => [$monad];
}
#[cfg(test)]
mod tests {
use std::vec::Vec;
use super::{monadic, Monad};
#[test]
fn it_works() {
let xs = (1..5).collect::<Vec<i32>>();
let zs = (&xs).into_iter().filter(|&v| v < &4).map(|v| v*2).collect::<Vec<i32>>();
let ys = monadic!{
v <- &xs;
guard v < &4;
Option::pure( v * 2)
}.collect::<Vec<i32>>();
assert_eq!(ys, zs);
}
}