Add shorthand and test IntTuple tparam defaults (#4896) - #4896
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meta-codesync Bot
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Sep 11, 2026
Summary:
In jax and other array libraries, it's not unusual to auto-promote scalars to empty-shape
arrays so that broadcasting works. For example, we can have
```
def add[S0: IntTuple, S1: IntTuple](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
and we want something like `f(3.141, y)` to produce the same shape as `y`.
The problem is that this doesn't actually work: if we pass a `float` for `x`, we wind up failing
to constrain `S0`, and it solves to gradual `IntTuple`, which means we drop the shape.
The workaround is to use a default:
```
def add[S0: IntTuple = [], S1: IntTuple = []](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
so that taking the scalar branch of the union leads to the unconstrained shape parameter being solved to `[]` by the default.
This diff adds support for the `[]` shorthand in this syntactic position for `IntTuple`-constrained type parameters, and verifies that it works as expected
Differential Revision: D119566820
meta-codesync Bot
pushed a commit
that referenced
this pull request
Sep 11, 2026
Summary:
In jax and other array libraries, it's not unusual to auto-promote scalars to empty-shape
arrays so that broadcasting works. For example, we can have
```
def add[S0: IntTuple, S1: IntTuple](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
and we want something like `f(3.141, y)` to produce the same shape as `y`.
The problem is that this doesn't actually work: if we pass a `float` for `x`, we wind up failing
to constrain `S0`, and it solves to gradual `IntTuple`, which means we drop the shape.
The workaround is to use a default:
```
def add[S0: IntTuple = [], S1: IntTuple = []](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
so that taking the scalar branch of the union leads to the unconstrained shape parameter being solved to `[]` by the default.
This diff adds support for the `[]` shorthand in this syntactic position for `IntTuple`-constrained type parameters, and verifies that it works as expected
Differential Revision: D119566820
meta-codesync Bot
pushed a commit
that referenced
this pull request
Sep 11, 2026
Summary:
In jax and other array libraries, it's not unusual to auto-promote scalars to empty-shape
arrays so that broadcasting works. For example, we can have
```
def add[S0: IntTuple, S1: IntTuple](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
and we want something like `f(3.141, y)` to produce the same shape as `y`.
The problem is that this doesn't actually work: if we pass a `float` for `x`, we wind up failing
to constrain `S0`, and it solves to gradual `IntTuple`, which means we drop the shape.
The workaround is to use a default:
```
def add[S0: IntTuple = [], S1: IntTuple = []](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
so that taking the scalar branch of the union leads to the unconstrained shape parameter being solved to `[]` by the default.
This diff adds support for the `[]` shorthand in this syntactic position for `IntTuple`-constrained type parameters, and verifies that it works as expected
Differential Revision: D119566820
meta-codesync Bot
pushed a commit
that referenced
this pull request
Sep 11, 2026
Summary:
In jax and other array libraries, it's not unusual to auto-promote scalars to empty-shape
arrays so that broadcasting works. For example, we can have
```
def add[S0: IntTuple, S1: IntTuple](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
and we want something like `f(3.141, y)` to produce the same shape as `y`.
The problem is that this doesn't actually work: if we pass a `float` for `x`, we wind up failing
to constrain `S0`, and it solves to gradual `IntTuple`, which means we drop the shape.
The workaround is to use a default:
```
def add[S0: IntTuple = [], S1: IntTuple = []](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
so that taking the scalar branch of the union leads to the unconstrained shape parameter being solved to `[]` by the default.
This diff adds support for the `[]` shorthand in this syntactic position for `IntTuple`-constrained type parameters, and verifies that it works as expected
Differential Revision: D119566820
Summary:
In jax and other array libraries, it's not unusual to auto-promote scalars to empty-shape
arrays so that broadcasting works. For example, we can have
```
def add[S0: IntTuple, S1: IntTuple](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
and we want something like `f(3.141, y)` to produce the same shape as `y`.
The problem is that this doesn't actually work: if we pass a `float` for `x`, we wind up failing
to constrain `S0`, and it solves to gradual `IntTuple`, which means we drop the shape.
The workaround is to use a default:
```
def add[S0: IntTuple = [], S1: IntTuple = []](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
so that taking the scalar branch of the union leads to the unconstrained shape parameter being solved to `[]` by the default.
This diff adds support for the `[]` shorthand in this syntactic position for `IntTuple`-constrained type parameters, and verifies that it works as expected
Differential Revision: D119566820
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meta-codesync Bot
pushed a commit
that referenced
this pull request
Sep 11, 2026
Summary:
In jax and other array libraries, it's not unusual to auto-promote scalars to empty-shape
arrays so that broadcasting works. For example, we can have
```
def add[S0: IntTuple, S1: IntTuple](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
and we want something like `f(3.141, y)` to produce the same shape as `y`.
The problem is that this doesn't actually work: if we pass a `float` for `x`, we wind up failing
to constrain `S0`, and it solves to gradual `IntTuple`, which means we drop the shape.
The workaround is to use a default:
```
def add[S0: IntTuple = [], S1: IntTuple = []](
x: Array[S0] | float, y: Array[S1] | float
) -> Array[broadcast(S0, S1)]
```
so that taking the scalar branch of the union leads to the unconstrained shape parameter being solved to `[]` by the default.
This diff adds support for the `[]` shorthand in this syntactic position for `IntTuple`-constrained type parameters, and verifies that it works as expected
Differential Revision: D119566820
|
According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
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Summary:
In jax and other array libraries, it's not unusual to auto-promote scalars to empty-shape
arrays so that broadcasting works. For example, we can have
and we want something like
f(3.141, y)to produce the same shape asy.The problem is that this doesn't actually work: if we pass a
floatforx, we wind up failingto constrain
S0, and it solves to gradualIntTuple, which means we drop the shape.The workaround is to use a default:
so that taking the scalar branch of the union leads to the unconstrained shape parameter being solved to
[]by the default.This diff adds support for the
[]shorthand in this syntactic position forIntTuple-constrained type parameters, and verifies that it works as expectedDifferential Revision: D119566820