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trcks.fp.monads.awaitable

Monadic functions for collections.abc.Awaitable.

Provides utilities for functional composition of asynchronous functions.

Example 
>>> import asyncio
>>> from trcks.fp.composition import pipe
>>> from trcks.fp.monads import awaitable as a
>>> async def read_from_disk() -> str:
...     await asyncio.sleep(0.001)
...     return "Hello, world!"
...
>>> def transform(s: str) -> str:
...     return f"Length: {len(s)}"
...
>>> async def write_to_disk(s: str) -> None:
...     await asyncio.sleep(0.001)
...
>>> async def main() -> str:
...     awaitable_str = read_from_disk()
...     return await pipe(
...         (
...             awaitable_str,
...             a.tap(lambda s: print(f"Read '{s}' from disk.")),
...             a.map_(transform),
...             a.tap_to_awaitable(write_to_disk),
...             a.tap(lambda s: print(f"Wrote '{s}' to disk.")),
...         ),
...     )
...
>>> output = asyncio.run(main())
Read 'Hello, world!' from disk.
Wrote 'Length: 13' to disk.
>>> output
'Length: 13'

construct(value)

Create a collections.abc.Awaitable from a value.

Parameters:

Returns:

Example 
>>> import asyncio
>>> from collections.abc import Awaitable
>>> from trcks.fp.monads import awaitable as a
>>> awtbl = a.construct("Hello, world!")
>>> isinstance(awtbl, Awaitable)
True
>>> asyncio.run(a.to_coroutine(awtbl))
'Hello, world!'
Source code in src/trcks/fp/monads/awaitable.py 
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def construct(value: _T) -> Awaitable[_T]:
    """Create a [collections.abc.Awaitable][] from a value.

    Args:
        value: The value to create the [collections.abc.Awaitable][] from.

    Returns:
        The [collections.abc.Awaitable][] created from the value.

    Example:
        >>> import asyncio
        >>> from collections.abc import Awaitable
        >>> from trcks.fp.monads import awaitable as a
        >>> awtbl = a.construct("Hello, world!")
        >>> isinstance(awtbl, Awaitable)
        True
        >>> asyncio.run(a.to_coroutine(awtbl))
        'Hello, world!'
    """
    return _construct(value)

map_(f)

Turn synchronous function into a function expecting and returning collections.abc.Awaitable.

Parameters:

Returns:

Note

The underscore in the function name helps to avoid collisions with the built-in function map.

Example 
>>> import asyncio
>>> from collections.abc import Awaitable
>>> from trcks.fp.monads import awaitable as a
>>> def transform(s: str) -> str:
...     return f"Length: {len(s)}"
...
>>> transform_mapped = a.map_(transform)
>>> awaitable_input = a.construct("Hello, world!")
>>> awaitable_output = transform_mapped(awaitable_input)
>>> isinstance(awaitable_output, Awaitable)
True
>>> asyncio.run(a.to_coroutine(awaitable_output))
'Length: 13'
Source code in src/trcks/fp/monads/awaitable.py 
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def map_(f: Callable[[_T1], _T2]) -> Callable[[Awaitable[_T1]], Awaitable[_T2]]:
    """Turn synchronous function into a function
    expecting and returning [collections.abc.Awaitable][].

    Args:
        f:
            The synchronous function to be transformed into
            a function expecting and returning a [collections.abc.Awaitable][].

    Returns:
        The given function transformed into
            a function expecting and returning a [collections.abc.Awaitable][].

    Note:
        The underscore in the function name helps to avoid collisions
        with the built-in function [map][].

    Example:
        >>> import asyncio
        >>> from collections.abc import Awaitable
        >>> from trcks.fp.monads import awaitable as a
        >>> def transform(s: str) -> str:
        ...     return f"Length: {len(s)}"
        ...
        >>> transform_mapped = a.map_(transform)
        >>> awaitable_input = a.construct("Hello, world!")
        >>> awaitable_output = transform_mapped(awaitable_input)
        >>> isinstance(awaitable_output, Awaitable)
        True
        >>> asyncio.run(a.to_coroutine(awaitable_output))
        'Length: 13'

    """

    def composed_f(value: _T1) -> Awaitable[_T2]:
        return construct(f(value))

    return map_to_awaitable(composed_f)

map_to_awaitable(f)

Turn collections.abc.Awaitable-returning function into function expecting and returning collections.abc.Awaitable.

Parameters:

Returns:

Example 
>>> import asyncio
>>> from collections.abc import Awaitable
>>> from trcks.fp.monads import awaitable as a
>>> async def write_to_disk(output: str) -> None:
...     await asyncio.sleep(0.001)
...     print(f"Wrote '{output}' to disk.")
...
>>> write_to_disk_mapped = a.map_to_awaitable(write_to_disk)
>>> awaitable_input = a.construct("Hello, world!")
>>> awaitable_output = write_to_disk_mapped(awaitable_input)
>>> isinstance(awaitable_output, Awaitable)
True
>>> asyncio.run(a.to_coroutine(awaitable_output))
Wrote 'Hello, world!' to disk.
Source code in src/trcks/fp/monads/awaitable.py 
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def map_to_awaitable(
    f: Callable[[_T1], Awaitable[_T2]],
) -> Callable[[Awaitable[_T1]], Awaitable[_T2]]:
    """Turn [collections.abc.Awaitable][]-returning function into
    function expecting and returning [collections.abc.Awaitable][].

    Args:
        f:
            The [collections.abc.Awaitable][]-returning function to be transformed into
            a function expecting and returning a [collections.abc.Awaitable][].

    Returns:
        The given function transformed into
            a function expecting and returning a [collections.abc.Awaitable][].


    Example:
        >>> import asyncio
        >>> from collections.abc import Awaitable
        >>> from trcks.fp.monads import awaitable as a
        >>> async def write_to_disk(output: str) -> None:
        ...     await asyncio.sleep(0.001)
        ...     print(f"Wrote '{output}' to disk.")
        ...
        >>> write_to_disk_mapped = a.map_to_awaitable(write_to_disk)
        >>> awaitable_input = a.construct("Hello, world!")
        >>> awaitable_output = write_to_disk_mapped(awaitable_input)
        >>> isinstance(awaitable_output, Awaitable)
        True
        >>> asyncio.run(a.to_coroutine(awaitable_output))
        Wrote 'Hello, world!' to disk.
    """

    async def mapped_f(awaitable: Awaitable[_T1]) -> _T2:
        return await f(await awaitable)

    return mapped_f

tap(f)

Turn synchronous function into a function expecting a collections.abc.Awaitable and returning the same collections.abc.Awaitable.

Parameters:

Returns:

Example 
>>> import asyncio
>>> from collections.abc import Awaitable
>>> from trcks.fp.monads import awaitable as a
>>> def print_string(s: str) -> None:
...     print(f"String: {s}")
...
>>> print_string_tapped = a.tap(print_string)
>>> awaitable_input = a.construct("Hello, world!")
>>> awaitable_output = print_string_tapped(awaitable_input)
>>> isinstance(awaitable_output, Awaitable)
True
>>> value = asyncio.run(a.to_coroutine(awaitable_output))
String: Hello, world!
>>> value
'Hello, world!'
Source code in src/trcks/fp/monads/awaitable.py 
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def tap(f: Callable[[_T1], object]) -> Callable[[Awaitable[_T1]], Awaitable[_T1]]:
    """Turn synchronous function into a function
    expecting a [collections.abc.Awaitable][] and
    returning the same [collections.abc.Awaitable][].

    Args:
        f:
            The synchronous function to be transformed into a function
            expecting a [collections.abc.Awaitable][] and
            returning the same [collections.abc.Awaitable][].

    Returns:
        The given function transformed into a function
            expecting a [collections.abc.Awaitable][] and
            returning the same [collections.abc.Awaitable][].

    Example:
        >>> import asyncio
        >>> from collections.abc import Awaitable
        >>> from trcks.fp.monads import awaitable as a
        >>> def print_string(s: str) -> None:
        ...     print(f"String: {s}")
        ...
        >>> print_string_tapped = a.tap(print_string)
        >>> awaitable_input = a.construct("Hello, world!")
        >>> awaitable_output = print_string_tapped(awaitable_input)
        >>> isinstance(awaitable_output, Awaitable)
        True
        >>> value = asyncio.run(a.to_coroutine(awaitable_output))
        String: Hello, world!
        >>> value
        'Hello, world!'
    """
    return map_(i.tap(f))

tap_to_awaitable(f)

Turn collections.abc.Awaitable-returning function into a function expecting a collections.abc.Awaitable and returning the same collections.abc.Awaitable.

Parameters:

Returns:

Example 
>>> import asyncio
>>> from collections.abc import Awaitable
>>> from trcks.fp.monads import awaitable as a
>>> async def write_to_disk(output: str) -> None:
...     await asyncio.sleep(0.001)
...     print(f"Wrote '{output}' to disk.")
...
>>> write_to_disk_tapped = a.tap_to_awaitable(write_to_disk)
>>> awaitable_input = a.construct("Hello, world!")
>>> awaitable_output = write_to_disk_tapped(awaitable_input)
>>> isinstance(awaitable_output, Awaitable)
True
>>> value = asyncio.run(a.to_coroutine(awaitable_output))
Wrote 'Hello, world!' to disk.
>>> value
'Hello, world!'
Source code in src/trcks/fp/monads/awaitable.py 
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def tap_to_awaitable(
    f: Callable[[_T1], Awaitable[object]],
) -> Callable[[Awaitable[_T1]], Awaitable[_T1]]:
    """Turn [collections.abc.Awaitable][]-returning function into a function
    expecting a [collections.abc.Awaitable][] and
    returning the same [collections.abc.Awaitable][].

    Args:
        f:
            The asynchronous function to be transformed into a function
            expecting a [collections.abc.Awaitable][] and
            returning the same [collections.abc.Awaitable][].

    Returns:
        The given function transformed into a function
            expecting a [collections.abc.Awaitable][] and
            returning the same [collections.abc.Awaitable][].

    Example:
        >>> import asyncio
        >>> from collections.abc import Awaitable
        >>> from trcks.fp.monads import awaitable as a
        >>> async def write_to_disk(output: str) -> None:
        ...     await asyncio.sleep(0.001)
        ...     print(f"Wrote '{output}' to disk.")
        ...
        >>> write_to_disk_tapped = a.tap_to_awaitable(write_to_disk)
        >>> awaitable_input = a.construct("Hello, world!")
        >>> awaitable_output = write_to_disk_tapped(awaitable_input)
        >>> isinstance(awaitable_output, Awaitable)
        True
        >>> value = asyncio.run(a.to_coroutine(awaitable_output))
        Wrote 'Hello, world!' to disk.
        >>> value
        'Hello, world!'
    """

    async def bypassed_f(value: _T1) -> _T1:
        _ = await f(value)
        return value

    return map_to_awaitable(bypassed_f)

to_coroutine(awtbl) async

Turn a collections.abc.Awaitable into a collections.abc.Coroutine.

This is useful for functions that expect a coroutine (e.g. asyncio.run).

Parameters:

Returns:

Note

The type collections.abc.Awaitable is a supertype of collections.abc.Coroutine.

Example

Transform an asyncio.Future into a collections.abc.Coroutine and run it:

>>> import asyncio
>>> from trcks.fp.monads import awaitable as a
>>> asyncio.set_event_loop(asyncio.new_event_loop())
>>> future = asyncio.Future[str]()
>>> future.set_result("Hello, world!")
>>> future
<Future finished result='Hello, world!'>
>>> coro = a.to_coroutine(future)
>>> coro
<coroutine object to_coroutine at 0x...>
>>> asyncio.run(coro)
'Hello, world!'
Source code in src/trcks/fp/monads/awaitable.py 
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async def to_coroutine(awtbl: Awaitable[_T]) -> _T:
    """Turn a [collections.abc.Awaitable][] into a [collections.abc.Coroutine][].

    This is useful for functions that expect a coroutine (e.g. [asyncio.run][]).

    Args:
        awtbl: The [collections.abc.Awaitable][] to be transformed
            into a [collections.abc.Coroutine][].

    Returns:
        The given [collections.abc.Awaitable][] transformed
            into a [collections.abc.Coroutine][].

    Note:
        The type [collections.abc.Awaitable][] is
        a supertype of [collections.abc.Coroutine][].

    Example:
        Transform an [asyncio.Future][] into a [collections.abc.Coroutine][] and run it:

        >>> import asyncio
        >>> from trcks.fp.monads import awaitable as a
        >>> asyncio.set_event_loop(asyncio.new_event_loop())
        >>> future = asyncio.Future[str]()
        >>> future.set_result("Hello, world!")
        >>> future
        <Future finished result='Hello, world!'>
        >>> coro = a.to_coroutine(future)
        >>> coro
        <coroutine object to_coroutine at 0x...>
        >>> asyncio.run(coro)
        'Hello, world!'
    """
    return await awtbl