From 650dd30062686a686a2e9d65079a50616ef58f45 Mon Sep 17 00:00:00 2001 From: Arseny Kapoulkine Date: Fri, 29 Oct 2021 12:56:35 -0700 Subject: [PATCH] Update getting-started and why for open source release --- docs/_pages/getting-started.md | 56 ++++++++++++---------------------- docs/_pages/why.md | 4 --- 2 files changed, 20 insertions(+), 40 deletions(-) diff --git a/docs/_pages/getting-started.md b/docs/_pages/getting-started.md index d580153..7dfbfec 100644 --- a/docs/_pages/getting-started.md +++ b/docs/_pages/getting-started.md @@ -4,25 +4,11 @@ title: Getting Started toc: true --- -To get started with Luau you need to install Roblox Studio, which you can download [here](https://www.roblox.com/create). - -## Creating a place - -If you just want to experiment with the language itself, you can create a simple baseplate game. - -
- -
+To get started with Luau you need to use `luau` command line binary to run your code and `luau-analyze` to run static analysis (including type checking and linting). You can download these from [Artifacts on a recent build](https://github.com/Roblox/luau/actions/workflows/release.yml). ## Creating a script -To create your own testing script, go to ServerScriptService in the explorer tree and add a Script object. - -
- -
- -Double-click on the script object and paste this: +To create your own testing script, create a new file with `.lua` as the extension: ```lua function ispositive(x) @@ -40,7 +26,9 @@ print(isfoo("bar")) print(isfoo(1)) ``` -Note that there are no warnings about calling ``ispositive()`` with a string, or calling ``isfoo()`` a number. +You can now run the file using `luau test.lua` and analyze it using `luau-analyze test.lua`. + +Note that there are no warnings about calling ``ispositive()`` with a string, or calling ``isfoo()`` a number. This is because the type checking uses non-strict mode by default, which is lenient in how it infers types used by the program. ## Type inference @@ -55,25 +43,18 @@ end print(ispositive(1)) print(ispositive("2")) - -function isfoo(a) - return a == "foo" -end - -print(isfoo("bar")) -print(isfoo(1)) ``` In ``strict`` mode, Luau will infer types based on analysis of the code flow. There is also ``nonstrict`` mode, where analysis is more conservative and types are more frequently inferred as ``any`` to reduce cases where legitimate code is flagged with warnings. -In this case, Luau will use the ``return x > 0`` statement to infer that ``ispositive()`` is a function taking an integer and returning a boolean. Similarly, it will use the ``return a == "foo"`` statement to infer that ``isfoo()`` is a function taking a string and returning a boolean. Note that in both cases, it was not necessary to add any explicit type annotations. +In this case, Luau will use the ``return x > 0`` statement to infer that ``ispositive()`` is a function taking a number and returning a boolean. Note that in this case, it was not necessary to add any explicit type annotations. -Based on Luau's type inference, the editor now highlights the incorrect calls to ``ispositive()`` and ``isfoo()``: +Based on Luau's type inference, the analysis tool will now flag the incorrect call to ``ispositive()``: -
- - -
+``` +$ luau-analyze test.lua +test.lua(7,18): TypeError: Type 'string' could not be converted into 'number' +``` ## Annotations @@ -110,9 +91,11 @@ result = ispositive(1) Oops -- we're returning string values, but we forgot to update the function return type. Since we've told Luau that ``ispositive()`` returns a boolean (and that's how we're using it), the call site isn't flagged as an error. But because the annotation doesn't match our code, we get a warning in the function body itself: -
- -
+``` +$ luau-analyze test.lua +test.lua(5,9): TypeError: Type 'string' could not be converted into 'boolean' +test.lua(7,9): TypeError: Type 'string' could not be converted into 'boolean' +``` The fix is simple; just change the annotation to declare the return type as a string: @@ -133,9 +116,10 @@ result = ispositive(1) Well, almost - since we declared ``result`` as a boolean, the call site is now flagged: -
- -
+``` +$ luau-analyze test.lua +test.lua(12,10): TypeError: Type 'string' could not be converted into 'boolean' +``` If we update the type of the local variable, everything is good. Note that we could also just let Luau infer the type of ``result`` by changing it to the single line version ``local result = ispositive(1)``. diff --git a/docs/_pages/why.md b/docs/_pages/why.md index 88eef56..4b097a5 100644 --- a/docs/_pages/why.md +++ b/docs/_pages/why.md @@ -24,7 +24,3 @@ As for the runtime, we had to rewrite the interpreter from scratch to get substa The garbage collector and the core libraries represent more of an incremental change, where we used Lua 5.1 as a baseline but we're continuing to rewrite these as well with performance in mind. While Luau doesn't currently implement JIT/AOT, this is likely to happen at some point; beyond the usual implementation challenges and security concerns, one significant limitation is that we don't have access to JIT on many platforms so for us maintaining excellent interpreted performance for gameplay and application code is more important than reaching peak FLOPS on numerical code. - -## Open source? - -Please note that at this time we are not ready to make Luau implementation publicly available in the source form. Right now the only interface to Luau is the Roblox engine (exposed in Roblox game client/server and Roblox Studio).