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Easy anonymous functions by partial application of operators
Python
Branch: master

README.rst

The Whatever Object

An easy way to make lambdas by partial application of python operators.

Inspired by Perl 6 one, see http://perlcabal.org/syn/S02.html#The_Whatever_Object

Usage

from whatever import _, that

# get a list of guys names
names = map(_.name, guys)
names = map(that.name, guys)

odd = map(_ * 2 + 1, range(10))

squares = map(_ ** 2, range(100))
small_squares = filter(_ < 100, squares)

best = max(tries, key=_.score)
sort(guys, key=-that.height)

factorial = lambda n: reduce(_ * _, range(2, n+1))

NOTE: chained comparisons cannot be implemented since there is no boolean overloading in python.

CAVEATS

In some special cases whatever can cause confusion:

_.attr # this makes callable
obj._  # this fetches '_' attribute of obj

_[key] # this works too
d[_]   # KeyError, most probably

_._    # short for attrgetter('_')
_[_]   # short for lambda d, k: d[k]

if _ == 'Any value':
    # You will get here, definitely
    # `_ == something` produces callable, which is true

[1, 2, _ * 2, None].index('hi') # => 2, since bool(_ * 2 == 'hi') is True

Also, whatever sometimes fails on late binding:

(_ * 2)('2') # -> NotImplemented
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