Macro sugars::cbtmap

macro_rules! cbtmap {
    ($key:expr => $value:expr; $i:ident <- $iter:expr) => { ... };
    ($key:expr => $value:expr; $i:ident <- $iter:expr, if $cond:expr) => { ... };
    ($key:expr => $value:expr; for $p:pat in $iter:expr) => { ... };
    ($key:expr => $value:expr; for $p:pat in $iter:expr, if $cond:expr) => { ... };
    ($key:expr => $value:expr; $p:pat in $iter:expr) => { ... };
    ($key:expr => $value:expr; $p:pat in $iter:expr, if $cond:expr) => { ... };
}

Macro to BTreeMap collection comprehensions

Supports 3 types of grammars: Haskell-like, Python-like, Just-in

Limitations

• Only 1 nested comprehensions
• Haskell-like cannot accept patterns

Examples:

use sugars::cbtmap;

let a = 10;
// Haskell-like
let x = cbtmap!{x => x+a; x <- 1..10};
let y = cbtmap!{x => x+a; x <- 1..10, if x%2 == 0};

// Python-like
let w = cbtmap!{x => x+a; for x in 1..10};
let z = cbtmap!{x => x+a; for x in 1..10, if x%2 == 0};

// Just-in
let w = cbtmap!{x => x+a; x in 1..10};
let z = cbtmap!{x => x+a; x in 1..10, if x%2 == 0};