external_functions

wrenfold.external_functions.declare_external_function(name: str, arguments: Iterable[Tuple[str, Type]], return_type: Type) → ExternalFunction

Declare an external function. External functions are implemented by the user outside of the code generation framework. They can be invoked on symbolic expressions, and their returned values can be utilized as part of further symbolic expressions.

At code-generation time, the user can override the format_custom_function_call formatter to specify how their external function is mapped to actual output code. This can be used to achieve certain customizations:

  • Mapping name to different functions in different target languages.

  • Inserting casts or type conversions around arguments.

By necessity, wrenfold must assume that external functions are pure (without side effects). Any two identical calls (ie. having the same function and argument lists) are assumed to be interchangeable, and will be de-duplicated during transpilation.

The arguments sequence specifies the names and expected types of the function arguments. The types may be:

Parameters:

  • name – String name for the function.

  • arguments – Iterable of (name, type) pairs that define the argument list of the function.

  • return_type – Return type of the function.

Returns:

An ExternalFunc object that can be invoked via the __call__ operator. The args to __call__ should have types matching arguments.

class wrenfold.external_functions.ExternalFunction(super_val: PyExternalFunction)

Callable object that represents a user-provided external function. External functions may be handwritten methods that live in the user’s codebase. Wrenfold can invoke these from generated code, provided they are declared with declare_external_function().

__call__(*args, **kwargs) → Any

Generate expressions to represent an invocation of self.

__init__(*args, **kwargs)

Overloaded function.

  1. __init__(self: wrenfold.gen.PyExternalFunction, name: str, arguments: list[tuple[str, object]], return_type: object) -> None

Construct with name, arguments, and return type.

  1. __init__(self: wrenfold.gen.PyExternalFunction, arg0: wrenfold.gen.PyExternalFunction) -> None

Copy constructor.