[Umbrella] std/collections

We landed the initial version of std/collections at #993

This issue is the umbrella issue for the remaining 28 APIs, which still need discussion. More detailed type definitions / docs / examples are available in the original proposal PR by @LionC.

ARRAYS

Transformations to Array

• mapNotNullish #1103
• takeFirstWhile
• takeLastWhile
• dropFirstWhile
• dropLastWhile
• filterNotNullish
• sortBy #1061
• runningReduce
• without #1074
• withoutAll #1100

Transformations to value

• findLastIndex #1060
• single
• firstNotNullishOf
• sumOf #1108
• maxBy
• minBy
• maxWith
• minWith
• maxOf #1144
• minOf

Number array transformations

• average moved to std/math proposal #1111

Transformations to other formats

• associateBy #1071
• windowed

RECORDS

Predicates

• includesValue

Transformations to Records

• filterValuesNotNullish
• deepMerge #1075

Groups

• reduceGroups
• aggregateGroups

If you’re interested in some specific items in the above, please pick one or more items, create a separate issue/PR for them, and keep discussion there.

[LionC]

I would like to implement single, is there any issue with this function?

I would just add the pointer that including (it) => true as a default for the predicate should be considered - that is what kt does because it allows a very smooth and readable transition from an (assumed) single-element array into that single element while also forcing you to handle what happens when that assumption is wrong:

// Assuming some cli that expects exactly one argument

const target = single(Deno.args)
    ?? error("Expected exactly one argument")

doMagic(target)

Also a note on the implementation: Make sure to short circuit when finding a second match instead of iterating through the rest of the array 😃

[kt3k]

The rest of items will be tracked in #1173.

Thanks @LionC for taking over the issue!