Alakazam
Functional programming sugar for Python.
Installing
A simple pip
command should do the trick. (In some cases, you may
need to use sudo
)
pip install alakazam
The Alakazam library does not, as of now, have any additional dependencies and is designed for Python 2 and 3.
Using
To use the stream functionality of Alakazam, import the alakazam
package. It is recommended that you alias the package as something
like zz
for easier typing.
To use the Alakazam lambda syntax, import the placeholders from
alakazam
explicitly.
import alakazam as zz from alakazam import _1, _2, _3, _4, _5
This library aims to make functional-style, and specifically
stream-oriented programming in Python prettier, more pleasant, and
easier on the eyes. Python has been capable of many functional
programming tasks, but it has always been a little bit awkward to use
those features for anything nontrivial. For instance, suppose we had
some list arr
, and we wanted to square every element of the list
and then keep only the even squares. This is how we might approach
this problem using Python's built-in functional tools.
list(filter(lambda x: x % 2 == 0, map(lambda x: x ** 2, arr)))
There's a lot of cruft here, with having to explicitly declare that we're using lambdas every time we need to make a function. Additionally, we have to read the code almost backward to understand what it's doing. While this backward sequencing of operations is fine in a language like Haskell (where pointfree notation hides the messy bracketing), in Python it would make much more sense if we could read our code in the normal order. This is where Alakazam comes in.
zz.of(arr).map(_1 ** 2).filter(_1 % 2 == 0).list()
Now the code reads left-to-right, and the lambdas are not nearly as
bulky. The zz.ZZ
(which is an alias for the class
alakazam.Alakazam
) is the entry point to any stream-based
operations you might want to perform with Alakazam. The of
method
wraps any iterable in an Alakazam instance. Then the map
and
filter
do the same thing as their global function
equivalents. Finally, the list
method converts the Alakazam
iterable into an ordinary Python list. The important thing is that,
now, a cursory left-to-right reading of the code yields "arr -> map ->
filter -> list", which is the sequence of operations we're actually
performing.
The lambda syntax is also significantly shortened. In cases where your
anonymous function merely uses operators, element access, and
attribute access, you can shorten it by using the placeholder
lambdas. The placeholder constants _1, _2, _3, _4, _5
, based
loosely on the C++ Boost placeholders with the same names, are each
defined as callable objects which return their nth argument. If you
need more than five arguments, you can use zz.arg(n) directly, which
is how the placeholders are implemented in the first place. These
placeholders can be used with (almost) any built-in Python operator,
and they can also be subscripted and have arbitrary attributes
accessed on them. All of these operations will be translated into an
anonymous function that performs the corresponding operation on its
arguments. So _1 ** 2
is a function that squares its first (and
only) argument, _1 + _2
is a function that adds two arguments
together, and _1.name == "Alakazam"
is a function which checks
whether its argument's name attribute is equal to "Alakazam".
Reference Material
The Alakazam Wiki lists the functions available to user
License
Please see LICENSE.txt
for licensing information.
Author
Alakazam was written by Silvio Mayolo.
Release Notes (0.7.0)
-
apply
reducer added, as per Issue #2. -
indices
andindex
, for returning indices of all matches in an iterable. -
join
,each
, andfirst
reducers added. -
split
function, combining the behaviors oftake
anddrop
, added. -
foldr
should perform significantly better when used on iterables which implement__reversed__
. - Several minor bugfixes involving utility functions.
Release Notes (0.6.0)
-
intersperse
andintertwine
transformers added. -
string
reducer added. -
assign
as a synonym forset
. - All classes are now new-style in Python 2 as well as Python 3.
Release Notes (0.5.0)
-
accumulate
can take an initial value now. -
accumulate
,filterfalse
, andzip_longest
now work correctly on Python 2. -
sum
now works on any type that has__add__
, including strings. -
compose
works correctly when the argument list is empty now. - Several functions that used to raise Python errors now raise
AlakazamError
. - Several bugfixes having to do with lazy evaluation in Python 2.
Release Notes (0.4.0)
- Trace functions
trace
,traceid
, andtracestack
, for debugging help. - New convenience syntax for invoking
bind
. -
map
can take multiple arguments now (Issue #1). -
withobject
transformer method. -
zipup
producer method. -
absorb
andconsume
reduction methods. -
swap
convenience function for tuples. - Terminology change: "Generator" to "Producer" to avoid confusion with the Python "generator" concept.
Release Notes (0.3.0)
- New convenience function
id
. - Boolean functions
not
,and_
,or_
, andxor
. -
min
andmax
methods onAlakazam
objects. - New
flatten
anditerate
methods. -
length
andnull
reduction methods. -
None
is now permitted as an argument to some functions where its behavior would have caused issues before.
Release Notes (0.2.0)
- Alakazam now uses Python 3 semantics for division (
from __future__ import division
) for consistency. - New functions
setindex
,getindex
, anddelindex
, for subscripted access and manipulation. - New utility function
raise_
. - Assignment lambdas with
set
, binder lambdas withbind
, and deletion lambdas withdelete
. - Errors are reported through
AlakazamError
now. - Changed
zip_longest
andcross_product
argument order to better match theitertools
equivalents. - Static methods on the
Alakazam
class can now be called globally. - Function
of_dict
provided to load dictionaries into Alakazam as lists of key-value 2-tuples.