wassname/jaxtyping
1
0
Fork 0
mirror of https://github.com/wassname/jaxtyping.git synced 2026-09-09 11:24:55 +08:00
Code Issues Packages Projects Releases Wiki Activity

Doc updates 2

Browse Source
This commit is contained in:
Patrick Kidger
2022-08-30 13:26:41 -07:00
parent 07e735797e
commit 140be9ecec
2 changed files with 24 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
FAQ.md
+22 -13
View File
@@ -1,5 +1,17 @@
# FAQ
## Does jaxtyping work with static type checkers like `mypy`/`pyright`/`pytype`?
There is partial support for these. An annotation of the form `dtype[array, shape]` should be treated as just `array` by a static type checker. Unfortunately full dtype/shape checking is beyond the scope of what static type checking is currently capable of.
(Note that at time of writing, `pytype` has a bug in that `dtype[array, shape]` is sometimes treated as `Any` rather than `array`. `mypy` and `pyright` both work fine.)
## How does jaxtyping interact with `jax.jit`?
jaxtyping and `jax.jit` synergise beautifully.
When calling JAX operations wrapped in a `jax.jit`, then the dtype/shape-checking will happen at trace time. (When JAX traces your function prior to compiling it.) The actual compiled code does not have any dtype/shape-checking, and will therefore still be just as fast as before!
## `flake8` is throwing an error.
In type annotations, strings are used for two different things. Sometimes they're strings. Sometimes they're "forward references", used to refer to a type that will be defined later.
@@ -8,18 +20,6 @@ Some tooling in the Python ecosystem assumes that only the latter is true, and w
In the case of `flake8`, at least, this is easily resolved. Multi-dimensional arrays (e.g. `f32[Array, "b c"]`) will throw a very unusual error (F722, syntax error in forward annotation), so you can safely just disable this particular error globally. Uni-dimensional arrays (e.g. `f32[Array, "x"]`) will throw an error that's actually useful (F821, undefined name), so instead of disabling this globally, you should instead prepend a space to the start of your shape, e.g. `f32[Array, " x"]`. `jaxtyping` will treat this in the same way, whilst `flake8` will now throw an F722 error that you can disable as before.
## Does jaxtyping work with static type checkers like `mypy`/`pyright`/`pytype`?
There is partial support for these. An annotation of the form `dtype[array, shape]` should be treated as just `array` by a static type checker. Unfortunately full dtype/shape checking is beyond the scope of what static type checking is currently capable of.
(Note that at time of writing, `pytype` has a bug in that `dtype[array, shape]` is sometimes treated as `Any` rather than `array`. The other two work fine.)
## How does jaxtyping interact with `jax.jit`?
jaxtyping and `jax.jit` synergise beautifully.
When calling JAX operations wrapped in a `jax.jit`, then the dtype/shape-checking will happen at trace time. (When JAX traces your function prior to compiling it.) The actual compiled code does not have any dtype/shape-checking, and will therefore still be just as fast as before!
## Does jaxtyping use [PEP 646](https://www.python.org/dev/peps/pep-0646/) (variadic generics)?
The intention of PEP 646 was to make it possible for static type checkers to perform shape checks of arrays. Unfortunately, this still isn't yet practical, so jaxtyping deliberately does not use this. (Yet?)
@@ -36,4 +36,13 @@ The real problem is that Python's static typing ecosystem is a complicated colle
5. The syntax for static typing is verbose. You have to write things like `Array[Float32, Unpack[AnyShape], Literal[3], Height, Width]` instead of `f32[Array, "... 3 height width"]`.
6. [The underlying type system has flaws](https://github.com/patrick-kidger/torchtyping/issues/37#issuecomment-1153294196). [The numeric tower is broken](https://stackoverflow.com/a/69383462); [int is not a number](https://github.com/python/mypy/issues/3186#issuecomment-885718629); [virtual base classes don't work](https://github.com/python/mypy/issues/2922); [complex lies about having comparison operations, so type checkers have to lie about that lie in order to remove them again](https://posita.github.io/numerary/0.4/whytho/); `typing.*` don't work with `isinstance`; co/contra-variance are baked into containers (not specified at use-time); `dict` is variadic despite... not being variadic; bool is a subclass of int (!); ... etc. etc.
6. [The underlying type system has flaws](https://github.com/patrick-kidger/torchtyping/issues/37#issuecomment-1153294196).
[The numeric tower is broken](https://stackoverflow.com/a/69383462);
[int is not a number](https://github.com/python/mypy/issues/3186#issuecomment-885718629);
[virtual base classes don't work](https://github.com/python/mypy/issues/2922);
[complex lies about having comparison operations, so type checkers have to lie about that lie in order to remove them again](https://posita.github.io/numerary/0.4/whytho/);
`typing.*` don't work with `isinstance`;
co/contra-variance are baked into containers (not specified at use-time);
`dict` is variadic despite... not being variadic;
bool is a subclass of int (!);
... etc. etc.