Transducers
are composable algorithmic transformations. They are independent from
the context of their input and output sources and specify only the
essence of the transformation in terms of an individual element. Because
transducers are decoupled from input or output sources, they can be
used in many different processes - collections, streams, channels,
observables, etc. Transducers compose directly, without awareness of
input or creation of intermediate aggregates.
In Python you can transduce anything you can iterate over (the
implementation of reduce included uses a for loop). This includes
generators and coroutines in addition to the vast majority of Python
collections. See below for an example of transducing over a generator.
For more information about Clojure transducers and transducer semantics see the introductory blog post and this video.
import transducers as Tfrom fractions import Fractiondef geometric_series(a, r):
power = 0
yield a while True:
power += 1
yield a * r**power
T.transduce(T.compose(T.take(3), T.map(float)),
T.append,
[],
geometric_series(Fraction(1, 1), Fraction(1, 2)))# > [1.0, 0.5, 0.25]
For more examples of use, see the test suite tests/transducer_tests.py.
Contributing
This library is open source, developed internally by Cognitect. Issues can be filed using GitHub Issues.
This project is provided without support or guarantee of continued
development.
Because transducers-python may be incorporated into products or client
projects, we prefer to do development internally and do not accept pull
requests or patches.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.