Add strutils.join for set type

[autumngray]

Seems like an oversight not to have strutils.join for set types, so here is an implementation.

[juancarlospaco]

Should go in setutils https://nim-lang.github.io/Nim/setutils.html

[autumngray]

Should go in setutils https://nim-lang.github.io/Nim/setutils.html

The procs in setutils all modify and/or produce sets whereas join produces a string, same as the other overloads in strutils. I think I would first try to import std/strutils when looking for a join():string. Putting it in setutils seems counterintuitive.

[metagn]

Seems like an oversight not to have strutils.join for set types

join depends on the iteration order of collections, which is not guaranteed to be a specific order for sets and happens to be ascending order for Nim's bitset implementation. This isn't really a problem, but a version of join that allows an arbitrary iterator would be more useful so it's more explicit for the user, but there isn't a clean API for this without at least a template.

[Araq]

This makes no sense to me, when is $ for sets not sufficient?

[autumngray]

To be specific, my use case was along these lines where I was expecting join to "just work":

type ApiParam = enum some allowed values
proc apiRequest(client: AsyncHttpClient, params: set[ApiParam]) =
  # params is a set, to constrain allowed api parameters. 
  let res = await client.get parseUri("https://example.com") ? {"paramset": params.join(",")}
  #...

Is this somehow to specific to go in std?

[Araq]

What about:

type ApiParam = enum some allowed values
proc apiRequest(client: AsyncHttpClient, params: set[ApiParam]) =
  # params is a set, to constrain allowed api parameters. 
  let res = await client.get parseUri("https://example.com") ? {"paramset": $params}
  #...

[autumngray]

No, that would give e.g. "{a, b, c}" instead of "a,b,c". The api endpoint doesn't like the extra spaces+curly braces.

[Araq]

Still feels weirdly specific though as the order for set iteration is pretty arbitrary, as others noticed.