2 stable releases
1.1.0 | Aug 10, 2020 |
---|---|
1.0.0 | Aug 6, 2020 |
0.0.1 |
|
#1943 in Rust patterns
73 downloads per month
Used in delayed-assert
17KB
403 lines
truthy
Check if a value is "truthy"
Behavior
// non-zero numbers are truthy
0u32.truthy() // false
0f32.truthy() // false
1u32.truthy() // true
1f32.truthy() // true
// empty strings are not truthy
"".truthy() // false
" ".truthy() // true
// Options are truthy if not None and their value is truthy
let none: Option<()> = None;
let falsy_inner = Some(false);
let truthy_inner = Some(true);
none.truthy() // false
falsy_inner.truthy() // false
truthy_inner.truthy() // true
// Results are truthy if Ok and value is truthy
let falsy_err: Result<(), _> = Err(false);
let truthy_err: Result<(), _> = Err(true);
let falsy_ok: Result<_, ()> = Ok(false);
let truthy_ok: Result<_, ()> = Ok(true);
falsy_err.truthy() // false
truthy_err.truthy() // false
falsy_ok.truthy() // false
truthy_ok.truthy() // true
// Empty vecs and arrays are falsy
let empty_array: [();0] = [];
let empty_vec: Vec<()> = Vec::new();
empty_array.truthy() // false
empty_vec.truthy() // false
// The truthy behavior of arrays and vecs also applies to tuples from size 0 to 12
let empty_tuple = ();
let not_empty_tuple = (1, "2", '3');
empty_tuple.truthy() // false
not_empty_tuple.truthy() // true
truthy!
macro
let my_bool = x.truthy() && y.truthy() || !z.truthy();
The above code can be a bit annoying, having to repeat .truthy()
multiple times. The truthy!
macro appends .truthy()
to save you time.
let my_bool = truthy!(x && y || !z);
You can run the example with cargo run --example truthy_macro
.
Limitations
The truthy!
macro cannot take non-boolean expressions. The only valid tokens in truthy!
are
(
, )
, !
, &&
, ||
, and identities. For example, the following would fail to compile.
truthy!(Some(1).unwrap() && 0 + 1);
To get around this, you would need to assign the expressions before using truthy!
.
let x = Some(1).unwrap();
let y = 0 + 1;
truthy!(x && y);
Features
and-or
This crate has an and-or
feature, which will provide the functions truthy_and
and truthy_or
to
any type that implements Truthy
and Sized
.
For example, true.truthy_and("It was truthy!")
returns Some("It was truthy!")
.
You can run the example with cargo run --features and-or --example and_or
.