M-Labs/nac3-spec
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Added #15

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pca006132 2021-06-09 09:45:13 +08:00 committed by pca006132
parent a642e37b9a
commit 1e80d8d285
1 changed files with 10 additions and 3 deletions
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@ -140,11 +140,18 @@ class Foo(EnvExperiment):
* Type variables are invariant, same as the default in Python. We disallow
covariant or contravariant. The compiler should mark as error if it encounters
a type variable used in kernel that is declared covariant or contravariant.
* Code region protected by a type check, such as `if type(x) == int:`, would
* A custom function `is_type(x, T)` would be provided to check whether `x` is an
instance of `T`, other methods like `type(x) == int` or `isinstance(x, int)`
would not compile. The function would be able to check generic types for
`list` and `tuple`. When running on the host, user can specify whether to use
a debug mode checking (recursively check all elements, which would be slower
for large lists) or performance mode which only check the first element of
each list. (#15)
* Code region protected by a type check, such as `if is_type(x, int):`, would
treat `x` as `int`, similar to how [typescript type guard](https://www.typescripttutorial.net/typescript-tutorial/typescript-type-guards/) works.
```python
def add1(x: Union[int, bool]) -> int:
if type(x) == int:
if is_type(x, int):
# x is int
return x + 1
else:
@ -152,7 +159,7 @@ class Foo(EnvExperiment):
return 2 if x else 1
```
* Generics are instantiated at compile time, all the type checks like
`type(x) == int` would be evaluated as constants. Type checks are not allowed
`is_type(x, int)` would be evaluated as constants. Type checks are not allowed
in area outside generics.
* Type variable cannot occur alone in the result type, i.e. must be bound to the
input parameters.