Teal – A statically-typed dialect of Lua

> Teal is a statically-typed dialect of Lua.

I was expecting Teal to be "Lua + type annotations", similar to Mypy. However from a quick look it does indeed seem to be a "dialect" in its own right. Teal is Lua-like and compiles to Lua, but there's more to it than just static types. Perhaps it's more similar to TypeScript?

For example, Teal replaces Lua's tables - the language's signature single, highly-flexible data structure - with separate arrays, tuples, maps, records and interfaces. It changes the variable scoping rules and even adds macro expressions.

Teal therefore seems substantially more complex than Lua. The author recognizes this in the conclusion to a recent presentation [0]: Lua is "small and simple", maybe Teal is "something else"? Lua is for "scripting", maybe Teal is better suited to "applications/libraries"?

[0] https://youtu.be/Uq_8bckDxaU?t=1618

Just a small note about mypy and python - annotations are first-class citizens in Python3 and are not tied to any particular type checking system such as mypy, but are instead a core part of the language and actually serve vital functions in frameworks and libraries that are used to check interfaces such as Pydantic and FastAPI (eg URL params).

Mypy is just one type checker for Python, but there are many others including pyright. In fact pyright is quickly becoming the dominant checker over mypy.

Am I right in thinking that Python's type annotation syntax originally came from Mypy though?

IIRC Mypy started off as a type annotation syntax and corresponding type checker for Python. Mypy's type annotations were adopted by Python itself (in version 3.5 - PEP 484), which reduced Mypy's role to be just a type checker.

Since then, type annotations have indeed become a core part of Python - not only are they used in frameworks and libraries, but are also required to use language features like @dataclass.