Stream: beginners

Topic: Why is Str.joinWith not in List?

Ryan Bates (Dec 07 2023 at 23:46):

I was looking in List for a way to join a list of strings together but was surprised it was in Str. I assumed functions in the standard lib were namespaced with the type they accept as the first argument (which is pretty intuitive to me).

If I understand the reason why it's in Str it will help me know where to look in the future.

Elias Mulhall (Dec 07 2023 at 23:53):

I had the same reaction.

Also in my 2d array library I have a function Array2D.joinWith that works the same way, it just take two joining strings to join both elements and rows. It feels a bit awkward that my function doesn't mirror the built-ins. I could do Array2D.Str.joinWith but that didn't seem worth it.

Brendan Hansknecht (Dec 07 2023 at 23:53):

I think it is for reading with intuitive name. List.joinWith would have nothing to do with strings. It would be for any arbitrary list.

Brendan Hansknecht (Dec 07 2023 at 23:53):

I guess it could be List.joinStrings but that doesn't feel better to me.

Ryan Bates (Dec 07 2023 at 23:55):

@Brendan Hansknecht there are a lot of functions in List that only work on Num (such as List.sum). I wouldn't want it to be Num.sum, but you could make the same argument for it.

Brendan Hansknecht (Dec 07 2023 at 23:58):

yeah, fair.

Brendan Hansknecht (Dec 07 2023 at 23:58):

Though I do think joinWith is too generic of a name to just put in List. (if it only works for strings)

Richard Feldman (Dec 08 2023 at 00:53):

the Str module currently depends on List and not the other way around

Richard Feldman (Dec 08 2023 at 00:54):

it's technically possible to cheat our way into circular dependncies in builtin modules (e.g. for Num.toStr, since Str certainly depends on Num) but I like to minimize that

Elias Mulhall (Dec 08 2023 at 00:55):

I don't think it's too bad the way it is. Where would you want the function to live ideally?

Ryan Bates (Dec 08 2023 at 00:58):

@Richard Feldman good to know, I didn't realize it was an internal dependency reason. I suppose it's a balance between an ideal interface and a clean implementation (if List.joinWith would be ideal).

Agus Zubiaga (Dec 08 2023 at 01:03):

I would expect List.joinWith to do the same as List.join but with the specified separator interspersed

Richard Feldman (Dec 08 2023 at 01:04):

yeah same :big_smile:

Last updated: Dec 21 2025 at 12:15 UTC