diff --git a/docs/support-for-type-packs-in-user-defined-type-functions.md b/docs/support-for-type-packs-in-user-defined-type-functions.md index 0f81d17..7d03e75 100644 --- a/docs/support-for-type-packs-in-user-defined-type-functions.md +++ b/docs/support-for-type-packs-in-user-defined-type-functions.md @@ -13,16 +13,16 @@ This limits the usage for packs as they are used often in the language, and thei ## Design -We introduce a new runtime type called `pack` to extend the support of type packs within the type runtime. +We introduce a new userdata called `pack` alongside `type` to extend the support of type packs within the type runtime. -Packs will have a `kind` property that specifies the kind of the pack. A pack can either be a `list` kind or a `variadic` kind. +`pack` instances will have a `kind` property that specifies the kind of the pack. A `pack` can either be of a `literal` kind or of a `variadic` kind. For example, consider a variadic type pack (e.g `...number`), in the new pack type, it will be represented as a `pack` with a `variadic` kind. -Or for a normal type pack such as `(number, string)`, it will be represented as a `pack` with a `list` kind. +Or for a normal type pack such as `(number, string)`, it will be represented as a `pack` with a `literal` kind. -`list` kind of packs will be able to contain other packs, or types more than one, whereas `variadic` type of packs will only contain *one* type. +`literal` packs will be able to contain other packs, or types more than one, whereas `variadic` kind of packs will only contain *one* type. -The user will be able to obtain the types within `pack`s using the `:unpack()` method, this method will return a table containing all the types or type packs within the pack. +The user will be able to obtain the `type`s within `pack`s using the `:unpack()` method, this method will return a table containing all the `type`s or `pack`s within the `pack`. In `variadic` kind of `pack`s, `:unpack()` will only return a table with one element. This is because variadic packs are essentially many elements of the same type. In user-defined type functions, type packs can be created by providing types or type packs that will be included within the pack. A pack will also be able to contain other packs, even packs of different kinds. @@ -32,10 +32,9 @@ In user-defined type functions, type packs can be created by providing types or Creating a type function that accepts type packs: ```luau -type function f(arg: type) - if not arg:is("pack") then error("The given argument is not a type pack!") end +type function f(arg: pack) + if typeof(arg) ~= "pack" then error("The given argument is not a type pack!") end local unpacked = arg:unpack() -- {string, number} - print(unpacked) end type a = f<(string, number)> ``` @@ -44,8 +43,9 @@ Creating a type function that returns a function with a type pack: ```luau type function f() - local newListPack = types.pack({types.string, types.number}) - local newVariadicPack = types.pack({types.any}, true) + local newPack = types.pack({types.string, types.number}) -- (string, number) + local newVariadicPack = types.pack({types.any}, true) -- ...any + local newfunc = types.newfunction() newfunc:setparameters({newPack}, newVariadicPack) newfunc:setreturns({newPack}, newVariadicPack) @@ -58,7 +58,7 @@ The pack type will also enable generic type packs to be provided to type functio Generic type pack arguments will pass the given type pack to the type function. ```luau -type function createCallback(args: type, returns: type) -- args will be a list pack, returns will be a variadic pack. +type function createCallback(args: pack, returns: pack) -- args will be a literal pack, returns will be a variadic pack. local newTable = types.newtable() local newfunc = types.newfunction() newfunc:setparameters({args}) @@ -74,35 +74,40 @@ If variadic type functions were to be implemented, type packs could be retrieved ```luau type function f(...) - local packed = {...} -- {type} - local firstPack = packed[1] -- type.kind: list - local secondPack = packed[2] -- type.kind: variadic + local packed = {...} -- {pack} + local firstPack = packed[1] -- pack.kind: literal + local secondPack = packed[2] -- pack.kind: variadic end type a = f<(string, number), ...number> ``` -## Updates to the types library and type userdata +Evaluating `typeof(...)` on a `pack` userdata will give the string `"pack"`. + +```luau +type function f(arg: pack) + print(typeof(arg)) -- "pack" +end +type a = f<(string, number)> +``` + +## New pack userdata + +### `pack` Instance + +| New/Update | Instance Properties & Methods | Type | Description | +| ------------- | ------------- | ------------- | ------------- | +| New | `kind` | `"literal" \| "variadic"` | indicates the kind of the `pack`. | +| New | `unpack()` | `{pack \| type}` | returns the `type`s contained within the `pack`, returns only one element if `kind` is `variadic`. | + +## Updates to the types library and the type userdata ### `types` Library | New/Update | Library Functions | Return Type | Description | | ------------- | ------------- | ------------- | ------------- | -| New | `pack(types: {type} isvariadic: boolean?)` | `type` | returns an immutable instance of a type pack; when `isvariadic` is true, `types` table can only have one type. | +| New | `pack(args: {pack \| type}, isvariadic: boolean?)` | `pack` | returns an immutable instance of a type pack; when `isvariadic` is true, `args` table can only have one `type`. | | Update | `newfunction(parameters: { head: {type}?, tail: type? }, returns: { head: {type}?, tail: type? }, generics: {type}?)` | `type` | `tail` arguments can now accept variadic packs. -### `type` Instance - -| New/Update | Instance Properties | Type | Description | -| ------------- | ------------- | ------------- | ------------- | -| Update | `tag` | `"nil" \| "unknown" \| "never" \| "any" \| "boolean" \| "number" \| "string" \| "singleton" \| "negation" \| "union" \| "intersection" \| "table" \| "function" \| "class" \| "thread" \| "buffer" \| "generic" \| "pack"` | Added `pack` as a possible tag | - -#### Pack `type` instance - -| New/Update | Instance Methods | Type | Description | -| ------------- | ------------- | ------------- | ------------- | -| New | `kind` | `"list" \| "variadic"` | indicates the kind of the pack. | -| New | `unpack()` | `{type}` | returns the types contained within the pack, returns only one element if `kind` is `variadic`. | - #### Function `type` instance | New/Update | Instance Methods | Return Type | Description |