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@ -6,34 +6,18 @@ A toy implementation is in [`toy-impl`](./toy-impl), requires python 3.9.
## Referencing Python Variables ## Referencing Python Variables
The kernel is allowed to read Python variables. The kernel is allowed to read host Python variables, but has to specify with
`global` before referencing them. This is to simplify and speed-up
implementation, and also warn the user about the variable being global. (prevent
calling the interpreter many times during compilation if there are many
references to host variables)
* Unbounded identifiers would be considered as Python variables, no object is Only primitive types and tuple/list of primitive types are allowed.
allowed, only primitive types and tuple/list of allowed types are allowed.
(not sure how to express the recursive concept neatly in English...)
* The value would be evaluated at compile time, subsequent modification
in the host would not be known by the kernel.
* Modification of global variable from within the kernel would be considered as
error.
* Calling non-RPC host function would be considered as an error. (RPC functions
must be annotated.)
Example code that would be disallowed: The value would be substituted at compile time, subsequent modification in the
```py host would not be known by the kernel.
from artiq.experiment import *
counter = 0
def get_id():
counter += 1
return counter
class Foo(EnvExperiment): Modification in kernel code to the global variables is not allowed.
@kernel
def run(self):
param = get_id()
# do something...
result = param
return result
```
## Class and Functions ## Class and Functions
* Class fields must be annotated: * Class fields must be annotated:
@ -55,8 +39,14 @@ class Foo(EnvExperiment):
floating point numbers are double by default. floating point numbers are double by default.
* RPCs: optional parameter type signature, require return type signature. * RPCs: optional parameter type signature, require return type signature.
* Function default parameters are not allowed, as changes to the default value * Function default parameters are not allowed, as changes to the default value
would not be kept across kernel calls, and that is a potential source of would not be kept across kernel calls, which is a potential source of
confusion. confusion. (maybe we can allow primitive default types?)
* Cannot construct objects within kernel code.
Questions:
* Can we construct objects within kernel code?
* Should we support function pointers? What about subtyping with function
pointers, and generic types?
## Built-in Types ## Built-in Types
* Primitive types include: * Primitive types include:
@ -85,7 +75,7 @@ class Foo(EnvExperiment):
i = 0 i = 0
a = t[i] a = t[i]
``` ```
* `range` (over numerical types) * `range` (over numerical types) (not sure if this is really useful)
### Numerical Types ### Numerical Types
* All binary operations expect the values to have the same type, no implicit * All binary operations expect the values to have the same type, no implicit
@ -113,9 +103,9 @@ class Foo(EnvExperiment):
``` ```
* Type variables can only be used in functions/methods, but not in classes. * Type variables can only be used in functions/methods, but not in classes.
* Type variable can be limited to a fixed set of types. A shorthand for one-time (this can be relaxed, only allow those with type variables fully defined
type variable limited to a fixed set of types is [union type & optional type](https://docs.python.org/3/library/typing.html#typing.Union). from the constructor)
e.g. `def run(self, a: Union[int, str])` * Type variable can be limited to a fixed set of types.
* Type variables are invariant, same as the default in Python. We disallow * Type variables are invariant, same as the default in Python. We disallow
covariant or contravariant. The compiler should mark as error if it encounters covariant or contravariant. The compiler should mark as error if it encounters
a type variable used in kernel that is declared covariant or contravariant. a type variable used in kernel that is declared covariant or contravariant.
@ -133,7 +123,8 @@ class Foo(EnvExperiment):
* Generics are instantiated at compile time, all the type checks like * Generics are instantiated at compile time, all the type checks like
`type(x) == int` would be evaluated as constants. Type checks are not allowed `type(x) == int` would be evaluated as constants. Type checks are not allowed
in area outside generics. in area outside generics.
* Type variable and union cannot occur alone in the result type. * Type variable cannot occur alone in the result type, i.e. must be bound to the
input parameters.
## Dynamic Dispatch ## Dynamic Dispatch
Type annotations are invariant, so subtype (derived types) cannot be used Type annotations are invariant, so subtype (derived types) cannot be used
@ -153,7 +144,7 @@ def bar(x: list[Base]) -> int:
sum += v.foo() sum += v.foo()
return sum return sum
# incorrect, the type signature of the list is `list[virtual[Base]]` # incorrect, this list cannot be typed (inhomogeneous)
bar([Base(), Derived()]) bar([Base(), Derived()])
``` ```
@ -168,6 +159,7 @@ inlining etc.
Type variables cannot be used inside `virtual[...]`, and type variables would not Type variables cannot be used inside `virtual[...]`, and type variables would not
range over `virtual[...]`. range over `virtual[...]`.
> Not sure what is the best syntax for `virtual[...]`
Example: Example:
```py ```py
@ -176,8 +168,6 @@ def bar2(x: list[virtual[Base]]) -> int:
for v in x: for v in x:
sum += v.foo() sum += v.foo()
return sum return sum
# correct
bar([Base(), Derived()])
``` ```