Metadata-Version: 2.1
Name: tryingsnake
Version: 0.5.0.dev0
Summary: Exception handling, the functional way.
Home-page: https://github.com/zero323/tryingsnake
Author: Maciej Szymkiewicz
Author-email: matthew.szymkiewicz@gmail.com
License: MIT
Description: TryingSnake
        ===========
        
        [![Build
        Status](https://travis-ci.org/zero323/tryingsnake.svg?branch=master)](https://travis-ci.org/zero323/tryingsnake)
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        Status](https://coveralls.io/repos/zero323/tryingsnake/badge.svg?branch=master&service=github)](https://coveralls.io/github/zero323/tryingsnake?branch=master)
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        Climate](https://codeclimate.com/github/zero323/tryingsnake/badges/gpa.svg)](https://codeclimate.com/github/zero323/tryingsnake)
        [![PyPI
        version](https://badge.fury.io/py/tryingsnake.svg)](https://badge.fury.io/py/tryingsnake)
        [![Conda Version](https://img.shields.io/conda/vn/conda-forge/tryingsnake.svg)](https://anaconda.org/conda-forge/tryingsnake)
        [![License
        MIT](https://img.shields.io/pypi/l/tryingsnake.svg)](https://github.com/zero323/tryingsnake/blob/master/LICENSE)
        
        A simple, `Try` implementation inspired by
        [scala.util.Try](https://www.scala-lang.org/api/current/scala/util/Try.html)
        
        Examples
        ========
        
        -   Wrap functions with arguments:
        
            ```python
            >>> from tryingsnake import Try, Try_, Success, Failure
            >>> from operator import add, truediv
            >>> Try(add, 0, 1)
            Success(1)
            >>> Try(truediv, 1, 0)  # doctest:+ELLIPSIS
            Failure(ZeroDivisionError(...))
            ```
        
        -   Avoid sentinel values:
        
            ```python
            >>> def mean_1(xs):
            ...     try:
            ...         return sum(xs) / len(xs)
            ...     except ZeroDivisionError as e:
            ...         return float("inf")  # What does it mean?
            >>> mean_1([])
            inf
            ```
        
            vs.
        
            ```python
            >>> def mean_2(xs):
            ...     return sum(xs) / len(xs)
            >>> Try(mean_2, [])  # doctest:+ELLIPSIS
            Failure(ZeroDivisionError(...))
            >>> Try(mean_2, ["foo", "bar"])  # doctest:+ELLIPSIS
            Failure(TypeError(...))
            ```
        
        -   Follow the happy path:
        
            ```python
            >>> def inc(x): return x + 1
            >>> def inv(x): return 1. / x
        
            >>> Success(1).map(inc).map(inv)
            Success(0.5)
        
            >>> Failure(Exception("e")).map(inc).map(inv)  # doctest:+ELLIPSIS
            Failure(Exception(...))
        
            >>> Success(-1).map(inc).map(inv)  # doctest:+ELLIPSIS
            Failure(ZeroDivisionError(...))
            ```
        
        -   Recover:
        
            ```python
            >>> def get(url):
            ...     if "mirror" in url:
            ...         raise IOError("No address associated with hostname")
            ...     return url
            >>> mirrors = ["http://mirror1.example.com", "http://example.com"]
            >>> Try(get, mirrors[0]).recover(lambda _: get(mirrors[1]))
            Success('http://example.com')
            ```
        
        -   Let them fail:
        
            ```python
            >>> from operator import getitem
            >>> Try(getitem, [], 0)  # doctest:+ELLIPSIS
            Failure(IndexError(...))
            >>> Try_.set_unhandled([IndexError])
            >>> Try(getitem, [], 0)
            Traceback (most recent call last):
                ...
            IndexError: list index out of range
            ```
        
        -   Make things (relatively) simple:
        
            ```python
            >>> import math
            >>> xs = [1.0, 0.0, "-1", -3, 2, 1 + 2j]
            >>> sqrts = [Try(math.sqrt, x) for x in xs]
            >>> [x.get() for x in sqrts if x.isSuccess]
            [1.0, 0.0, 1.4142135623730951]
            >>> def get_etype(e):
            ...     return Try(lambda x: type(x).__name__, e)
            >>> [x.recoverWith(get_etype).get() for x in sqrts if x.isFailure]
            ['TypeError', 'ValueError', 'TypeError']
            ```
        
        -   Inline exception handling:
        
            ```python
            >>> from tryingsnake.curried import Try
            >>> map(Try(str.split), ["foo bar", None])  # doctest:+ELLIPSIS
            <map at ...>
            ```
        
        -   Decorate your functions:
        
            ```python
            >>> from tryingsnake.curried import Try as try_
            >>> @try_
            ... def scale_imag(x):
            ...     return complex(x.real, x.imag * 2)
            >>> [scale_imag(x) for x in [1 + 2j, "3", 42 + 0j]]
            [Success((1+4j)), Failure(AttributeError("'str' object has no attribute 'real'")), Success((42+0j))]
            ```
        
        -   Wrap generator objects:
        
            ```python
            >>> def get_nth(xs, i):
            ...     yield xs[i]
            >>> xs = [1, 3, 5, 7]
            >>> Try(get_nth(xs, 3))
            Success(7)
            >>> Try(get_nth(xs, 11))
            Failure(IndexError('list index out of range'))
            >>> def f():
            ...     divisor = 1
            ...     while True:
            ...         divisor_ = yield 1 / divisor
            ...         divisor = divisor_ if divisor_ is not None else 1
            >>> g = f()
            >>> next(g)  # Should be primed
            1.0
            >>> Try(g, 2)
            Success(0.5)
            >>> Try(g, 0)
            Failure(ZeroDivisionError('division by zero'))
            ```
        
        Installation
        ============
        
        This package is available on PYPI:
        
            pip install tryingsnake
        
        and conda-forge:
        
            conda install -c conda-forge tryingsnake
        
        
        Dependencies
        =======
        
        `tryingsnake` supports Python 3.6 or later and
        requires no external dependencies.
        
        License
        =======
        
        MIT, See
        [LICENSE](https://github.com/zero323/tryingsnake/blob/master/LICENSE)
        
        FAQ
        ===
        
        -   Q: Is this project production-ready?
        -   A: Sure, for some definition of production-ready. It is a toy project.
            It has decent test coverage, stable API, and in general seems to do
            what is expected to do. But it is not widely used, and the API design
            and overall idea are rather unpythonic.
        -   Q: Why to use mixedCase method names instead of lowercase
            recommended by PEP8?
        -   A: Mostly to make switching between Python and Scala code as
            painless as possible.
        -   Q: What is the runtime cost?    
            A: As of [0088286](https://github.com/zero323/tryingsnake/commit/00882862d655cd3d77ea730449f498883ed584d5) (releases 0.3 and 0.4 suffered from
            severe performance regression caused by using `typing.Generic` as a base of
            try. See [#18](https://github.com/zero323/tryingsnake/issues/18) for details)
            rough numbers for simple tasks look as follows:
        
            ```
            Python 3.7.5 (default, Oct 27 2019, 15:43:29)
            Type 'copyright', 'credits' or 'license' for more information
            IPython 7.11.0 -- An enhanced Interactive Python. Type '?' for help.
            In [1]: def identity(x): return x
            In [2]: from tryingsnake import Try
            In [3]: %timeit for i in range(1_000_000): identity(i)
            59.8 ms ± 683 µs per loop (mean ± std. dev. of 7 runs, 10 loops each)
        
            In [4]: %timeit for i in range(1_000_000): Try(identity, i)
            408 ms ± 4.14 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
            ```
        
            and execution time is dominated by the initializer:
        
            ```
            In [5]: import cProfile
            In [6]: cProfile.run("for i in range(1_000_000): Try(identity, i)")
                     4000003 function calls in 0.961 seconds
        
               Ordered by: standard name
        
               ncalls  tottime  percall  cumtime  percall filename:lineno(function)
              1000000    0.078    0.000    0.078    0.000 <ipython-input-1-abafd771428d>:1(identity)
                    1    0.263    0.263    0.961    0.961 <string>:1(<module>)
              1000000    0.094    0.000    0.094    0.000 __init__.py:234(__init__)
              1000000    0.480    0.000    0.698    0.000 __init__.py:352(Try)
              1000000    0.046    0.000    0.046    0.000 {built-in method builtins.callable}
                    1    0.000    0.000    0.961    0.961 {built-in method builtins.exec}
                    1    0.000    0.000    0.000    0.000 {method 'disable' of '_lsprof.Profiler' objects}
            ```
        
            This is quite a lot for simple functions so you should probably avoid it in such cases, where raw performance is important. It is still possible to amortize the cost in such cases, for example using composition:
        
            ```python
            from toolz.functoolz import compose
            from tryingsnake import Try
        
            Try(compose(str.split, str.lower, str.strip), " Foo BAR FooBar ")
            ```
        
            Memory overhead (as measured by [memory-profiler](https://pypi.org/project/memory-profiler/)) looks as follows:
        
            ```
            Line #    Mem usage    Increment   Line Contents
            ================================================
             6     37.9 MiB     37.9 MiB   @profile
             7                             def f():
             8    155.5 MiB      0.8 MiB       [Try(identity, i) for i in range(1_000_000)]
            ```
        
            compared to:
        
            ```
            Line #    Mem usage    Increment   Line Contents
            ================================================
             6     37.9 MiB     37.9 MiB   @profile
             7                             def f():
             8     77.4 MiB      1.0 MiB       [identity(i) for i in range(1_000_000)]
             ```
        
Platform: UNKNOWN
Classifier: Programming Language :: Python :: 3
Classifier: Development Status :: 3 - Alpha
Classifier: License :: OSI Approved :: MIT License
Description-Content-Type: text/markdown
