dry-python/returns 0.15.0

Version 0.15.0 aka The initial HKT release

on GitHub

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