Callbag factory that converts any number of pullable source into a single pullable source that emits the Cartesian product of the sources. This is unlikely to work correctly for listenable sources.
This is just a very thin wrapper around callbag-flatten, whose README shows the basic pattern of calling map inside map, and then flattening. Callbags allow us to have nice memory efficiency with extreme flexibility and composability.
Recursively creating Cartesian callbags from Cartesian callbags, using this simple library, is not very ergonomic—you might get unexpected nesting. In those situations, just grab @avinashcodes' callbag-flat-map, which gives you full control over combining Cartesian callbags with other callbags.
In a Node.js project, run
$ npm install --save callbag-cartesian-project
Optional boolean fortranOrder (defaults to true) switches between Fortran ordering (first source alternates the fastest) and C ordering (first source changes the slowest). Compare the default Fortran ordering:
const cartesian = require('callbag-cartesian-product');
const { pipe, fromIter, forEach } = require('callbag-basics'); // from `npm i callbag-basics`
pipe(
cartesian(fromIter([ 0, 1, 2 ]), fromIter('rgb'), fromIter([ true, false ])),
forEach(x => console.log(x)),
)
// [ 0, 'r', true ]
// [ 1, 'r', true ]
// [ 2, 'r', true ]
// [ 0, 'g', true ]
// [ 1, 'g', true ]
// [ 2, 'g', true ]
// [ 0, 'b', true ]
// [ 1, 'b', true ]
// [ 2, 'b', true ]
// [ 0, 'r', false ]
// [ 1, 'r', false ]
// [ 2, 'r', false ]
// [ 0, 'g', false ]
// [ 1, 'g', false ]
// [ 2, 'g', false ]
// [ 0, 'b', false ]
// [ 1, 'b', false ]
// [ 2, 'b', false ]to C ordering:
pipe(
cartesian(false, fromIter([ 0, 1, 2 ]), fromIter('rgb'), fromIter([ true, false ])),
forEach(x => console.log(x)),
)
// [ 0, 'r', true ]
// [ 0, 'r', false ]
// [ 0, 'g', true ]
// [ 0, 'g', false ]
// [ 0, 'b', true ]
// [ 0, 'b', false ]
// [ 1, 'r', true ]
// [ 1, 'r', false ]
// [ 1, 'g', true ]
// [ 1, 'g', false ]
// [ 1, 'b', true ]
// [ 1, 'b', false ]
// [ 2, 'r', true ]
// [ 2, 'r', false ]
// [ 2, 'g', true ]
// [ 2, 'g', false ]
// [ 2, 'b', true ]
// [ 2, 'b', false ]callbag-basicsand links to articles therein- GitHub's search results for "callbag"
- André Staltz's "Why we need callbags"