# Naming Some\[Trait\] and \*SomeTypeList\[Trait\] **URL:** \ **Category:** Standard Library\ **Tags:** discussion, mojo-language-design\ **Created:** [April 16, 2026, 3:10pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972 "2026-04-16T15:10:06Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![christoph\_schlumpf](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/christoph_schlumpf/32/274_2.png) [@christoph\_schlumpf](https://forum.modular.com/u/christoph_schlumpf)\ **Post date:** [April 16, 2026, 3:10pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/1 "2026-04-16T15:10:06Z")
Based on the following Discord post I start this discussion to decide on the naming of `Some` and `SomeTypeList`. > **[Discord - Group Chat That’s All Fun & Games](https://discord.com/channels/1087530497313357884/1224434323193594059/1494331156412498081)** > > Discord is great for playing games and chilling with friends, or even building a worldwide community. Customize your own space to talk, play, and hang out. `Some` can be used to implicitly declare a type parameter while `*SomeTypeList` can be used to implicitly declare variadic type parameters. While I think the current naming is viable, `*SomeTypeList` is quite verbose. Possible alternatives (updated): - `Some`/`*SomeTypeList` (the current naming) - `Some`/`*SomeTypes` (less verbose) - `SomeType`/`*SomeTypes` (more consistent?) - `Some`/`*Each` (short and expressive?) - `Impl`/`*ImplList` - `Impl`/`*ImplEach` - … Maybe not feasible: - `Type`/`*Types` (`Type` is a reserved keyword) - `Some`/`*Some` (same name for both not possible?) Example ```mojo # current naming def foo[T: Copyable, //](arg: T) -> Int: ... def foo(arg: Some[Copyable]) -> Int: ... def bar[*Ts: Copyable](*args: *Ts) -> Int: ... def bar(*args: *SomeTypeList[Copyable]) -> Int: ... # one alternativ def bar(*args: *Each[Copyable]) -> Int: ... ``` The great thing is that `Some` and `SomeTypeList` are „just“ comptime type alias and not hardcoded compiler keywords. BTW: `Some` is already in the stdlib for quite some 😉 time while `SomeTypeList` is new. [[mojo-lang] Enable autoparam of variadic pack type lists. · modular/modular@b964941 · GitHub](https://github.com/modular/modular/commit/b9649411c487fe5e57db0a90b04a90d6658509bc) The `Some` name was already discussed and decided on in this issue: [[Feature Request] Rename `InstanceOf` to express trait implementation · Issue #5166 · modular/modular · GitHub](https://github.com/modular/modular/issues/5166) `some` is used in Swift too. ---
**Author:** ![martinvuyk](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/martinvuyk/32/48_2.png) [@martinvuyk](https://forum.modular.com/u/martinvuyk)\ **Post date:** [April 16, 2026, 3:53pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/2 "2026-04-16T15:53:37Z")
> `SomeType`/`*SomeTypes` I can see the value in going in this direction due to consistency and clarity but I’m not a fan of making `Some` more verbose given we already have quite descriptive and long-named traits. I’m not opposed to doing it though, since it does provide value in bringing clarity for people unfamiliar with the concept. I’m 100% pro `*SomeTypes` above the other cited options, it still follows the lead of our current and alternative `Some` naming. However, if somebody does come up with an interesting alternative (for `Some` or `SomeTypes`) I think it’s worth hearing. ---
**Author:** ![christoph\_schlumpf](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/christoph_schlumpf/32/274_2.png) [@christoph\_schlumpf](https://forum.modular.com/u/christoph_schlumpf)\ **Post date:** [April 16, 2026, 4:10pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/3 "2026-04-16T16:10:36Z")
In an ideal world I would prefer `Some`/`*Some` but I think that‘s not possible with the current language constructs and implementation as comptime type alias. ---
**Author:** ![christoph\_schlumpf](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/christoph_schlumpf/32/274_2.png) [@christoph\_schlumpf](https://forum.modular.com/u/christoph_schlumpf)\ **Post date:** [April 16, 2026, 5:39pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/4 "2026-04-16T17:39:23Z")
I added your proposal to the list. ---
**Author:** ![rd4com](https://avatars.discourse-cdn.com/v4/letter/r/cdc98d/32.png) [@rd4com](https://forum.modular.com/u/rd4com)\ **Post date:** [April 16, 2026, 8:49pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/5 "2026-04-16T20:49:37Z")
What about something like `Type[Movable]` and `Types[Movable]`, i know that “Type” is an keyword we might need later, just an idea 👍 ---
**Author:** ![duck\_tape](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/duck_tape/32/432_2.png) [@duck\_tape](https://forum.modular.com/u/duck_tape)\ **Post date:** [April 17, 2026, 10:49am UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/6 "2026-04-17T10:49:52Z")
Why not `Impl` and `ImplList`? Reading back through the old Github thread, there was never a strong reason not to use `Impl` and `Some` now has two strikes against it: collision with `Optional` variants (in our heads at least), and it doesn’t translate nicely to `SomeList`. ```mojo def foo[T: Copyable, //](arg: T) -> Int: ... def foo(arg: Impl[Copyable]) -> Int: ... def bar[*Ts: Copyable](*args: *Ts) -> Int: ... def bar(*args: *ImplList[Copyable]) -> Int: ... ``` ---
**Author:** ![christoph\_schlumpf](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/christoph_schlumpf/32/274_2.png) [@christoph\_schlumpf](https://forum.modular.com/u/christoph_schlumpf)\ **Post date:** [April 17, 2026, 11:13am UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/7 "2026-04-17T11:13:24Z")
OK, I add it to to list of possible alternatives. ---
**Author:** ![JulianJS](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/julianjs/32/1032_2.png) [@JulianJS](https://forum.modular.com/u/JulianJS)\ **Post date:** [April 17, 2026, 8:27pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/8 "2026-04-17T20:27:11Z")
IMO The current version feels a little weird - Some - SomeTypeList I think “Each” fits nice. - Some - Each And to throw in another option which combines other suggestions: - Impl - ImplEach This feels like a very good combination being short and still clear! 🤓 ---
**Author:** ![christoph\_schlumpf](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/christoph_schlumpf/32/274_2.png) [@christoph\_schlumpf](https://forum.modular.com/u/christoph_schlumpf)\ **Post date:** [April 17, 2026, 10:14pm UTC](https://forum.modular.com/t/naming-some-trait-and-sometypelist-trait/2972/9 "2026-04-17T22:14:28Z")
I’m in favor of `Some`/`*Each`: - `Some` is well established, short and no abbreviation. Semantics: `Some` type that conforms to the trait. - `*Each` complements `Some` as it is short and no abbreviation too. It implies plurality. Semantics: `Each` type conforms to the trait. IMO the names must be short and easy to recognize. This allows for a “concise” implicit alternative to the more complex and verbose explicit syntax. Example: ```mojo def foo[T: Copyable, //](arg: T) -> Int: ... def foo(arg: Some[Copyable]) -> Int: ... def bar[*Ts: Copyable](*args: *Ts) -> Int: ... def bar(*args: *Each[Copyable]) -> Int: ... ```