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returns v0.15.0 Release Notes

Release Date: 2020-10-21 // over 3 years ago

  • 🔋 Features

    ➕ Adds Higher Kinded Types partial support

    💥 Breaking : drops python3.6 support

    💥 Breaking : makes our mypy plugin not optional, but required!

    💥 Breaking : changes all RequiresContext-based type arguments order,
    previously we used to specify _EnvType as the first type argument,
    now it is the last one. This is done to respect new HKT rules

    💥 Breaking : renames .rescue to .lash

    💥 Breaking : removes all old interfaces from primitives/interfaces.py,
    👉 use new typeclasses instead

    💥 Breaking : Maybe is fully reworked to be lawful

    💥 Breaking : removes value_or pointfree method,
    because it is impossible to express with HKT

    💥 Breaking : removes .value_or, .unwrap, and .failure methods
    from FutureResult and RequiresContext-based types,
    👻 because we do require these methods to raise an exception on failure,
    👻 but these methods were lazy and did not raise the required exception

    💥 Breaking : changes how is_successful is typed:
    now we allow any Unwrappable interface instances there,
    including custom ones

    💥 Breaking : changes UnwrapFailedError constructor,
    now it does accept an Unwrappable instance instead of a BaseContainer

    💥 Breaking : removes .fix method from all containers,
    🚚 also removes fix pointfree function

    💥 Breaking : Removes coalesce function,
    because it is impossible to properly type it

    💥 Breaking : Removes all Context* based types with .ask() method,
    👉 use new .ask() methods on the Reader-based containers

    💥 Breaking : Now Future and FutureResult can be awaited multiple times

    💥 Breaking : Removes .unify() method from several containers,
    👉 use unify() pointfree function instead

    💥 Breaking : Removes .from_iterable method from all containers,
    👍 instead adds better iterables support,
    we now have returns.iterables module with Fold helper

    💥 Breaking : Renames property empty to no_args of
    all RequiresContext-based classes

    ➕ Adds new public interfaces: see returns.interfaces

    ➕ Adds methods package with several helpful things inside

    ➕ Adds FutureSuccess and FutureFailure unit functions
    to be similar to Result and IOResult

    ➕ Adds .swap method to Result, IOResult, FutureResult,
    and other result based containers

    Adds .modify_env method to all RequiresContext* types

    ➕ Adds .rescue to Maybe

    ➕ Adds .equals methods to types that can be compared directly:
    Result, Maybe, IO, IOResult

    Adds missing from_requires_context_future_result to RequiresContext

    Adds .from_optional and .bind_optional to Maybe container

    Adds __slots__ to UnwrapFailedError with halted_container

    🔄 Changes flatten to work with KindN and any possible container

    ➕ Adds a helper to test traces to our pytest plugin

    ➕ Adds cond function to pointfree and methods packages

    ➕ Adds compose_result HKT method and pointfree function

    ➕ Adds unify HKT pointfree function

    ➕ Adds bimap pointfree function

    Adds unwrap_or_failure function to methods package

    ➕ Adds collect_trace helper function for better development experience

    ➕ Adds hypothesis intergration and pre-defined "monad laws as values"

    ➕ Adds assert_equal method to our pytest plugin

    🛠 Bugfixes

    • 💥 Breaking : fixes serious typing issue and changes how flow works
    • 💥 Breaking : fixes serious typing issue and changes how pipe works,
      now it has a hard limit of 20 parameters
    • 🛠 Fixes that RequiresContextFutureResult was not supported by pytest plugin
    • 🛠 Fixes incorrect partial behaviour in an edge case, #618
    • 🛠 Fixes that .apply method of IOResult was working incorrectly,
      it was returning IOFailure(2)
      as a result of IOFailure(1).apply(IOFailure(2))
    • 🛠 Fixes bug that safe(tap(...)) was revealing invalid types sometimes

    Misc

    • ➕ Adds a lot of new typetests
    • Checks that now all math laws are checked for all types
    • 🔄 Changes docs structure, adds new Interfaces, HKT, and Methods pages
    • Changed __str__ method in BaseContainer class to __repr__ method
    • ➕ Adds Quickstart guide