Macro curry

macro_rules! curry {
    ($($arg:ident ->)+ * $body:block) => { ... };
    ($($arg:ident ->)+ @$ret:ty $body:block) => { ... };
}

Creates a curried function.

The given function definition should be specified in the form

(arg ->)+ (*|@return_type) {
    function_body
}

No types are specified on the function parameters. An explicit return type can be specified with a type preceded by an @; specifying * will deduce the return type. The macro will not perform any type conversions.

Examples

let add_3 = curry!(a -> b -> c -> * {
  a + b + c
});

assert_eq!(add_3(13)(71)(26), 110);

let haiku = curry!(a -> b -> c -> @String {
  let lines = vec![a, b, c];
  lines.join("\n")
});

assert_eq!(haiku("The first cold shower")
                ("Even the monkey seems to want")
                ("A little coat of straw"),

                "The first cold shower\n\
                 Even the monkey seems to want\n\
                 A little coat of straw");

let add_3 = curry!(a -> b -> c -> @usize {
  a + b + c // error; evaluates to i32
});

assert_eq!(add_3(13)(71)(26), 110);