diff --git a/docs/compatibility.md b/docs/compatibility.md index 0f2dd76b..a7a1df17 100644 --- a/docs/compatibility.md +++ b/docs/compatibility.md @@ -7,7 +7,7 @@ Our overall goal is to incorporate features from the later versions of Lua when - ✔️ - the feature is available in Luau - ❌ - the feature is not available in Luau because we don't believe it makes sense to include it -- ⁉️ - the feature is not available in Luau because of compatibility/sandboxing concerns +- 😞 - the feature is not available in Luau because of compatibility/sandboxing concerns - 🔜 - the feature is not available in Luau yet but we'd like to include it and are possibly working on it - 🤷‍♀️ - the feature is not available in Luau yet; we don't have strong opinions on it so it might make it at some point @@ -36,9 +36,9 @@ Lua 5.2 | emergency garbage collector | ❌ | Luau runs in environments where handling memory exhaustion in emergency situations is not tenable | | goto statement | ❌ | this complicates the compiler due to handling of locals and doesn't address a significant need | | finalizers for tables | ❌ | no `__gc` support due to sandboxing and performance/complexity | -| no more fenv for threads or functions | ⁉️ | we love this, but it breaks compatibility | +| no more fenv for threads or functions | 😞 | we love this, but it breaks compatibility | | tables honor the `__len` metamethod | ❌ | performance implications, no strong use cases -| hex and `\z` escapes in strings (also `\u` for Unicode) | ✔️ | | +| hex and `\z` escapes in strings | ✔️ | | | support for hexadecimal floats | 🤷‍♀️ | no strong use cases | | order metamethods work for different types | ❌ | no strong use cases and more complicated semantics + compat | | empty statement | ✔️ | | @@ -61,6 +61,7 @@ Lua 5.3 | feature | status | notes | |---------|--------|------| +| `\u` escapes in strings | ✔️ | | | integers (64-bit by default) | ❌ | backwards compatibility and performance implications | | bitwise operators | ❌ | `bit32` library covers this | | basic utf-8 support | ✔️ | we include `utf8` library and other UTF8 features | @@ -88,13 +89,13 @@ Lua 5.4 | new implementation for math.random | ✔️ | our RNG is based on PCG, unlike Lua 5.4 which uses Xoroshiro | | optional `init` argument to `string.gmatch` | 🤷‍♀️ | no strong use cases | | new functions `lua_resetthread` and `coroutine.close` | ❌ | not useful without to-be-closed variables | -| coersions string-to-number moved to the string library | ⁉️ | we love this, but it breaks compatibility | +| coersions string-to-number moved to the string library | 😞 | we love this, but it breaks compatibility | | new format `%p` in `string.format` | 🤷‍♀️ | no strong use cases | | `utf8` library accepts codepoints up to 2^31 | 🤷‍♀️ | no strong use cases | -| The use of the `__lt` metamethod to emulate `__le` has been removed | ⁉️ | breaks compatibility and doesn't seem very interesting otherwise | +| The use of the `__lt` metamethod to emulate `__le` has been removed | 😞 | breaks compatibility and doesn't seem very interesting otherwise | | When finalizing objects, Lua will call `__gc` metamethods that are not functions | ❌ | no `__gc` support due to sandboxing and performance/complexity | | The function print calls `__tostring` instead of tostring to format its arguments. | 🔜 | | -| By default, the decoding functions in the utf8 library do not accept surrogates. | ⁉️ | breaks compatibility and doesn't seem very interesting otherwise | +| By default, the decoding functions in the utf8 library do not accept surrogates. | 😞 | breaks compatibility and doesn't seem very interesting otherwise | Lua has a beautiful syntax and frankly we're disappointed in the ``/`` which takes away from that beauty. Taking syntax aside, `` isn't very useful in Luau - its dominant use case is for code that works with external resources like files or sockets, but we don't provide such APIs - and has a very large complexity cost, evidences by a lot of bug fixes since the initial implementation in 5.4 work versions. `` in Luau doesn't matter for performance - our multi-pass compiler is already able to analyze the usage of the variable to know if it's modified or not and extract all performance gains from it - so the only use here is for code readability, where the `` syntax is... suboptimal.