Feature request: sortBy function in std/collections

[andreubotella]

Is your feature request related to a problem? Please describe.

Array.prototype.sort sorts an array using a callback that takes two elements of the array and must return a number, whose sign will determine their sort order. This is not very intuitive, especially when you just want to compare the elements by the natural ordering of one of their fields, for example.

A related issue is that, if you don't pass a callback to Array.prototype.sort, the default behavior is to stringify the array elements, which is very counterintuitive in cases like [10, 20, 110].sort().

Describe the solution you'd like

Add a sortBy utility function in std/collections, whose callback parameter maps an array element to a value which will then be compared with the mapped values for other array elements, much like the key callback parameter to Python's list.sort. The mapped values would be compared using their natural ordering (a.k.a. by using the regular comparison operators).

And since (as per above), Array.prototype.sort without a callback also has problems, the callback attribute to sortBy should also be optional and default to the identity function.

Describe alternatives you've considered

An alternative would be to have a function that would take a mapping callback and return a callback that can be used with Array.prototype.sort. This would incur additional complexity that probably isn't needed.

Additional context

N/A