Beartype 0.3.0

Changes include:

Compatibility Broken

• None. This release preserves backward compatibility with the prior
  stable release.

Dependencies Bumped

• None. Not that we had any dependencies to begin with, of course.

Features Added

• Deep sequence type-checking. The @beartype.beartype decorator
  now type-checks both the shallow types and deep contents of
  parameters and return values annotated with typing-based sequences
  in guaranteed constant time, exploiting a variant of the well-known
  coupon collector's problem by randomly type-checking one item at each
  nesting level of each sequence on each call of each decorated
  callable. Currently supported typing-based sequences include:
  • typing.List.
  • typing.MutableSequence.
  • typing.Sequence.
• Human-readable exception messages on type-checking failures. When
  passed parameters or returning values violating PEP-compliant type
  hints, callables decorated by the @beartype.beartype decorator now
  raise human-readable exceptions exhibiting the exact cause(s) of those
  violations, including violations deeply nested in subcontainers (e.g.,
  "@beartyped pep_hinted() parameter pep_hinted_param=[([37],)]
  violates PEP type hint
  typing.List[typing.Sequence[typing.MutableSequence[str]]], as list
  item 0 tuple item 0 list item 0 value "37" not str.") Currently
  supported typing type hints that now generate human-readable
  exception messages include:
  • typing.List.
  • typing.MutableSequence.
  • typing.Optional.
  • typing.Sequence.
  • typing.Union.

Features Optimized

• Deep sequence type-checking. Under Python >= 3.8, the
  @beartype.beartype decorator generates optimal code deeply
  type-checking items contained in nested subsequences (e.g.,
  List[List[List[str]]]) with PEP 572-style assignment expressions --
  the controversial syntactic change that would prompt Guido to
  voluntarily abdicate his ancestral leadership role as BDFL. Thanks to
  beartype 0.3.0, assignment expressions have finally proved their
  real-world utility. This optimization has been quantitatively profiled
  to generate type-checking code at least twice as fast as the
  equivalent code generated under Python < 3.8 in the case of
  triply-nested sequences. Since this performance gap only increases as
  the nesting level increases, a doubling of performance is only the
  minimum improvement observable under Python >= 3.8. Sequences more
  than triply-nested can expect a comparably dramatic speedup.
• User-defined callables not accepting positional arguments. A
  local variable previously unconditionally defined in the bodies of all
  wrapper functions dynamically generated and returned by the
  @beartype.beartype decorator is now only conditionally defined in
  the bodies of wrapper functions wrapping user-defined callables
  accepting one or more positional arguments.
• Wrapper function generation. Wrapper functions are now confined to
  internally access only the exact set of global attributes they
  specifically require rather than the complete set of such attributes
  accessible from the private beartype._decor.main submodule.

Features Deprecated

• None. You don't deprecate what ain't broke.

Features Removed

• None. You don't remove what's worth keepin'.

Tests Improved

• Deep type-checking. Exhaustive tests guaranteeing the sanity of
  deep type-checking of all supported combinations of typing sequences
  and typing unions have been added.
• Human-readable exception messages on type-checking failures.
  Exhaustive tests guaranteeing the readability of these messages have
  also been added by iteratively matching these messages against
  iterables of arbitrary regular expressions expected to both match and
  not match these messages.

Documentation Revised

• Installation instructions, including new Gentoo-specific
  installation instructions courtesy the third-party raiagent overlay.

API Changed

• Nothing. Not publicly, anyway. Violate privacy encapsulation and
  the cuddly kitten gets it!

(Spherical orthodontics adhere to a glib gibberings of orthopedic ornithopters!)