Created
April 13, 2016 15:32
-
-
Save anonymous/6a5f21c31e3467f4f78ca4f8f385d915 to your computer and use it in GitHub Desktop.
Shared via Rust Playground
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#![feature(trace_macros)] | |
#![feature(log_syntax)] | |
//trace_macros!(true); | |
macro_rules! id {($e : expr) => ($e)} | |
macro_rules! vecc {($($t:tt)*) => (Vecc{v:vec!($($t)*)})} | |
macro_rules! mdo { | |
//{{$(let $pat : pat = $expr : expr;)+}; $($rest : tt)*} => ({let $pat = $expr; mdo!{$($rest)*}}); | |
{{let $($rst : tt)+}; $($rest : tt)*} => (id!({let $($rst)+ mdo!{$($rest)*}})); | |
{$x : expr} => ($x); | |
//{$pat : pat = $b : expr; $x : expr} => ($b.and_then(|$pat| $x)); | |
{ $pat : pat = $b : expr; $($b1 : tt)+} => ($b.and_then(|$pat| mdo!{$($b1)+ })) | |
} | |
//trait Unit[M<_>] { fn unit<T>(T) -> M<T>; } | |
#[derive(Debug)] | |
struct Vecc<T>{v: Vec<T>} | |
impl<T> Vecc<T> { | |
pub fn new() -> Vecc<T> {Vecc{v: Vec::new()}} | |
fn push(&mut self, value: T) {self.v.push(value)} | |
pub fn and_then<U, F: Fn(&T) -> Vecc<U>>(&self, f : F) -> Vecc<U> { | |
let mut out = Vecc::new(); | |
for x in &self.v { | |
for y in f(x).v { | |
out.push(y); | |
} | |
} | |
out | |
} | |
} | |
fn main() { | |
fn sq(x: u32) -> Option<u32> { Some(x * x) } | |
fn nope(_: u32) -> Option<u32> { None } | |
let v : Vecc<(i32,i32)> = mdo!{a = vecc!(1,2); b = vecc!(3,4); vecc!((*a,*b))}; | |
println!("{:?}", v); | |
let _ : Result<i32,i32> = mdo!{a = Ok(3); b = Ok(a); {println!("{}",a+b);Ok(b+a)}}; | |
let _ : Option<u32> = mdo!{{let nn = Some(2);}; n = nn; m = sq(n); Some(m)}; | |
assert_eq!(mdo!{n = Some(2); m = sq(n); sq(m)}, Some(16)); | |
assert_eq!(mdo!{a = Some(2); a = sq(a); sq(a)}, Some(16)); | |
assert_eq!(mdo!{a = Some(2); a = sq(a); nope(a)}, None); | |
assert_eq!(mdo!{a = Some(2); a = nope(a); sq(a)}, None); | |
assert_eq!(mdo!{a = None; a = sq(a); sq(a)}, None); | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment