Stream: API design

Topic: URL routing

Richard Feldman (Sep 20 2023 at 12:57):

I just thought of an interesting API design for server routing from a URL:

when Route.fromUrl url is
    Get ["users", username] -> # e.g. /users/rtfeldman
    Get ["users", username, "profile"] -> # e.g. /users/foo/profile
    Get ["search"] if Dict.contains params "q" -> # e.g. /search?q=blah
    Post ["register"] -> # has to be exactly /register

Richard Feldman (Sep 20 2023 at 12:59):

then if you need additional parsing (like for Get ["users", userId] where userId is an integer) you'd do that after the initial match, e.g. running Num.fromStr on them as necessary

Fábio Beirão (Sep 20 2023 at 14:14):

I assume that for checking such guards (is number, is number within the expected range, etc), you would create a private helper function and use the same if Dict.contains ..... strategy with that private function. This way, you don't have to "step into" the match and then have no way to step back to check if a later route would match. Would that work?

Brendan Hansknecht (Sep 20 2023 at 14:33):

Sounds reasonable, but I would be concerned of perf. Routers get hit a lot. Even the tiniest of perf gains can help. I wonder if routers in other languages do something special to keep perf really high here. Just in general questioning if a full flat match over a list of strings will be performant. Might be fine, just questioning.

Richard Feldman (Sep 20 2023 at 15:13):

it's a good question...I wonder if a future compiler optimization could be a good idea for when on a list of strings

Richard Feldman (Sep 20 2023 at 15:15):

Str.split path "/" should be fast and the substrings should all be slices, so no allocations aside from the 1 for the list itself

Richard Feldman (Sep 20 2023 at 15:15):

and then "GET" to Get should be fast too

Richard Feldman (Sep 20 2023 at 15:16):

so I think the only question would be how quickly the List Str can be matched up with a particular when branch like this, and that's what I think maybe a compiler optimization could improve in the future

Brendan Hansknecht (Sep 20 2023 at 15:28):

Very fair. I guess everything should be slices, so that should be pretty decent.

Brendan Hansknecht (Sep 20 2023 at 15:28):

*slices or clones of parts of small strings

Brendan Hansknecht (Sep 20 2023 at 15:28):

Honestly, the dictionary lookup may be likely to be the slowest part

Richard Feldman (Sep 20 2023 at 15:47):

for the query?

Richard Feldman (Sep 20 2023 at 15:47):

that could also just be a List

Brendan Hansknecht (Sep 20 2023 at 15:51):

Yeah, probably should be a VecMap

Luke Boswell (Sep 20 2023 at 20:46):

I like how simple that router is.

Last updated: Jul 26 2025 at 12:14 UTC