Zipped

Utility for recursively unzipping tuples, Options of tuples and Results of tuples.

Install

cargo add zipped

Usage

This crate is quiet straightforward.

Unzipping (((A, B), C), ...)

If you have a left- or right-recursively zipped tuple, you can use UnzipInto::unzip_into to turn it into a non-recursive tuple. This works for up to 26 tuple elements.

use zipped::UnzipInto;

let (a, b, c) = ((1, 2), 3).unzip_into(); // left-recursive
let (a, b, c) = (1, (2, 3)).unzip_into(); // right-recursive

Unzipping Option<(((A, B), C), ...)>

If you have an Option that contains a left- or right-recursively zipped tuple, you can also use UnzipInto::unzip_into to turn it into an Option of a non-recursive tuple. This also works for up to 26 tuple elements.

use zipped::UnzipInto;

let zipped = Some(1).zip(Some(2)).zip(Some(3));

match zipped.unzip_into() {
    Some((a, b, c)) => {}
    None => {}
}

While it's also possible to unzip Options with right-recursively zipped tuples, these don't occur naturally since Option::zip is left-recursive.

Unzipping Result<(((A, B), C), ...), E>

If you have a Result that contains a left- or right-recursively zipped tuple, you can also use UnzipInto::unzip_into to turn it into a Result of a non-recursive tuple. This also works for up to 26 tuple elements.

use zipped::UnzipInto;

let zipped = Ok::<_, ()>(1)
    .and_then(|a| Ok((a, 2)))
    .and_then(|ab| Ok((ab, 3)));

match zipped.unzip_into() {
    Ok((a, b, c)) => {}
    Err(_) => {}
}

Again, while it's also possible to unzip Results with right-recursively zipped tuples, I found that these occur much less often.

Limitations

• Type inference. The compiler cannot automatically infer T in UnzipInto<T>. Eventually, you will need to specify the return value's arity.
• Maximum arity. UnzipFrom is implemented for tuples of up to 26 elements.
• Strict. It only works for completely zipped tuples where each tuple contains 2 elements and only the left (or the right) element can be another tuple, i.e. it does not work for ((A, B), C, D).

License

Copyright 2022 Glacyr B.V.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.