Patterns

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

Installation

pip install patterns

Usage

frompatternsimportpatterns, Mismatch@patternsdeffactorial():
if0: 1ifnisint: n*factorial(n-1)
if []: []
if [x] +xs: [factorial(x)] +factorial(xs)
if {'n': n, 'f': f}: f(factorial(n))
assertfactorial(0) ==1assertfactorial(5) ==120assertfactorial([3,4,2]) == [6, 24, 2]
assertfactorial({'n': [5, 1], 'f': sum}) ==121factorial('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