Patterns

Pattern matching for python. Works in Python 2.7, 3.3+ and pypy.

Installation

pip install patterns

Usage

from patterns import patterns, Mismatch

@patterns
def factorial():
    if 0: 1
    if n is int: n * factorial(n-1)
    if []: []
    if [x] + xs: [factorial(x)] + factorial(xs)
    if {'n': n, 'f': f}: f(factorial(n))

assert factorial(0) == 1
assert factorial(5) == 120
assert factorial([3,4,2]) == [6, 24, 2]
assert factorial({'n': [5, 1], 'f': sum}) == 121

factorial('hello') # raises Mismatch

See tests for more examples.

TODO

• docs
• aliases for structures
• destructure objects
• name parameter
• better handling of Mismatch passing to function env
• non-strict dict matching