@thi.ng/transducers
Advanced tools
[!NOTE] This is one of 190 standalone projects, maintained as part of the @thi.ng/umbrella monorepo and anti-framework.
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Lightweight transducer implementations for ES6 / TypeScript.
This library provides altogether ~130 transducers, reducers, sequence generators (ES6 generators/iterators) and additional supporting functions for composing data transformation pipelines.
The overall concept and many of the core functions offered here are directly inspired by the original Clojure implementation by Rich Hickey, though the implementation does heavily differ (also in contrast to some other JS based implementations) and dozens of less common, but generally highly useful operators have been added. See full list below.
Furthermore, most transducers & reducers provided here accept an
optional input iterable, which allows them to be used directly as
transformers instead of having to wrap them in one of the execution
functions (i.e. transduce()/transduceRight(), reduce()/reduceRight(),
iterator(), run(), step()). If called this way, transducer functions
will return a transforming ES6 iterator (generator) and reducing functions
will return a reduced result of the given input iterable.
STABLE - used in production
Search or submit any issues for this package
Thanks to a PR and related
issue by
@gavinpc-mindgrub, various transducers
functions have been fixed for the case when they're invoked with an empty
string as input iterable. Furthermore,
flatten() is
always treating strings as atomic values now, whereas before top-level strings
would be split into individual characters.
BREAKING CHANGES:
interpolate iterator for keyframe interpolation has been renamed
to tween. In its place there's a new higher order transducer called
interpolate, incl. syntax-sugar versions interpolateHermite and
interpolateLinear.wrapLeft, wrapRight and wrapBoth
iterators have been removed.wrap iterator has been renamed to wrapSides and has a new
signature/arguments, more aligned with the ones listed below.The following new iterators have been added:
extendSidespadSidessymmetricSeveral previously included internal support functions have been migrated to the @thi.ng/arrays package. You'll need to update your imports if you've been using any of these directly. Note that some of these functions also have changes to their arg order. See changelog.
Functions using randomness now all support an optional PRNG
implementation of the IRandom interface from the
@thi.ng/random
package.
yarn add @thi.ng/transducers
ES module import:
<script type="module" src="https://cdn.skypack.dev/@thi.ng/transducers"></script>
For Node.js REPL:
const transducers = await import("@thi.ng/transducers");
Package sizes (brotli'd, pre-treeshake): ESM: 8.89 KB
Several projects in this repo's /examples directory are using this package:
| Screenshot | Description | Live demo | Source |
|---|---|---|---|
 | Interactive image processing (adaptive threshold) | Demo | Source |
 | ASCII art raymarching with thi.ng/shader-ast & thi.ng/text-canvas | Demo | Source |
 | Large ASCII font text generator using @thi.ng/rdom | Demo | Source |
 | Figlet-style bitmap font creation with transducers | Demo | Source |
 | Self-modifying, animated typographic grid with emergent complex patterns | Demo | Source |
 | 2D transducer based cellular automata | Demo | Source |
 | Heatmap visualization of this mono-repo's commits | Source | |
 | Filterable commit log UI w/ minimal server to provide commit history | Demo | Source |
 | Basic crypto-currency candle chart with multiple moving averages plots | Demo | Source |
 | Color palette generation via dominant color extraction from uploaded images | Demo | Source |
 | Interactive visualization of closest points on ellipses | Demo | Source |
 | Interactive inverse FFT toy synth | Demo | Source |
 | Fiber-based cooperative multitasking basics | Demo | Source |
 | Visualization of different grid iterator strategies | Demo | Source |
 | hdom update performance benchmark w/ config options | Demo | Source |
 | Realtime analog clock demo | Demo | Source |
 | Interactive pattern drawing demo using transducers | Demo | Source |
 | Various hdom-canvas shape drawing examples & SVG conversion / export | Demo | Source |
| Custom dropdown UI component w/ fuzzy search | Demo | Source | |
| Isolated, component-local DOM updates | Demo | Source | |
 | Basic hiccup-based canvas drawing | Demo | Source |
 | Canvas based Immediate Mode GUI components | Demo | Source |
 | Animated sine plasma effect visualized using contour lines | Demo | Source |
 | Transforming JSON into UI components | Demo | Source |
 | Randomized space-filling, nested grid layout generator | Demo | Source |
 | Browser REPL for a Lispy S-expression based mini language | Demo | Source |
 | Worker based, interactive Mandelbrot visualization | Demo | Source |
 | Mastodon API feed reader with support for different media types, fullscreen media modal, HTML rewriting | Demo | Source |
 | CLI util to visualize umbrella pkg stats | Source | |
 | Parser grammar livecoding editor/playground & codegen | Demo | Source |
 | RGB waveform image analysis | Demo | Source |
 | Polygon to cubic curve conversion & visualization | Demo | Source |
 | Animated, iterative polygon subdivisions & visualization | Demo | Source |
 | Procedural stochastic text generation via custom DSL, parse grammar & AST transformation | Demo | Source |
 | Unison wavetable synth with waveform editor | Demo | Source |
| Demonstates various rdom usage patterns | Demo | Source | |
 | Minimal rdom-canvas animation | Demo | Source |
 | rstream & transducer-based FSM for converting key event sequences into high-level commands | Demo | Source |
 | rdom & hiccup-canvas interop test | Demo | Source |
| Full umbrella repo doc string search w/ paginated results | Demo | Source | |
 | rdom powered SVG graph with draggable nodes | Demo | Source |
 | Defining & using basic Web Components (with shadow DOM) via @thi.ng/rdom & @thi.ng/meta-css | Demo | Source |
 | Responsive image gallery with tag-based Jaccard similarity ranking | Demo | Source |
 | Generative audio synth offline renderer and WAV file export | Demo | Source |
 | Animated Voronoi diagram, cubic splines & SVG download | Demo | Source |
| Minimal rstream dataflow graph | Demo | Source | |
 | Minimal demo of using rstream constructs to form an interceptor-style event loop | Demo | Source |
 | Interactive grid generator, SVG generation & export, undo/redo support | Demo | Source |
| rstream based UI updates & state handling | Demo | Source | |
 | Minimal rstream sync() example using rdom | Demo | Source |
 | 2D scenegraph & shape picking | Demo | Source |
 | Shader-AST meta-programming techniques for animated function plots | Demo | Source |
 | Fork-join worker-based raymarch renderer (JS/CPU only) | Demo | Source |
 | Simplistic SVG bar chart component | Demo | Source |
 | SVG path parsing & dynamic resampling | Demo | Source |
 | Additive waveform synthesis & SVG visualization with undo/redo | Demo | Source |
 | hdom based slide deck viewer & slides from my ClojureX 2018 keynote | Demo | Source |
 | Multi-layer vectorization & dithering of bitmap images | Demo | Source |
 | Triple store query results & sortable table | Demo | Source |
 | rdom & WebGL-based image channel editor | Demo | Source |
 | WebGL multi-colored cube mesh | Demo | Source |
 | Drawing to floating point offscreen / multi-pass shader pipeline | Demo | Source |
 | WebGL instancing, animated grid | Demo | Source |
 | WebGL MSDF text rendering & particle system | Demo | Source |
 | 1D Wolfram automata with OBJ point cloud export | Demo | Source |
 | XML/HTML/SVG to hiccup/JS conversion | Demo | Source |
import { comp, distinct, filter, map } from "@thi.ng/transducers";
// compose transducer
xform = comp(
filter((x) => (x & 1) > 0), // odd numbers only
distinct(), // distinct numbers only
map((x) => x * 3) // times 3
);
import { transduce, push } from "@thi.ng/transducers";
// collect into array (push)
transduce(xform, push(), [1, 2, 3, 4, 5, 4, 3, 2, 1]);
// [ 3, 9, 15 ]
// re-use same xform, but collect into ES6 Set
transduce(xform, conj(), [1, 2, 3, 4, 5, 4, 3, 2, 1]);
// Set { 3, 9, 15 }
import { iterator } from "@thi.ng/transducers";
// or apply as transforming iterator
// no reduction, only transformations
[...iterator(xform, [1, 2, 3, 4, 5])]
// [ 3, 9, 15]
// alternatively provide an input iterable and
// use xform as transforming iterator
[...filter((x) => /[A-Z]/.test(x), "Hello World!")]
// ["H", "W"]
import { step } from "@thi.ng/transducers";
// single step execution
// returns undefined if transducer returned no result for this input
// returns array if transducer step produced multiple results
f = step(xform);
f(1) // 3
f(2) // undefined
f(3) // 9
f(4) // undefined
f = step(take)
This example uses the @thi.ng/geom package for quick SVG generation.
import { asSvg, svgDoc, circle, polyline } from "@thi.ng/geom";
// source values
const values = [5, 10, 4, 8, 20, 2, 11, 7];
// interpolate values and transform into 2D points
const vertices = [...iterator(
comp(
interpolateHermite(10),
mapIndexed((x, y) => [x, y])
),
// duplicate first & last vals (1x LHS / 2x RHS)
// this is only needed for hermite interpolation
// (see doc string for `interpolateHermite`)
extendSides(values, 1, 2)
)];
// generate SVG
asSvg(
svgDoc(
{ width: 800, height: 200, "stroke-width": 0.1 },
// interpolated points as polyline
polyline(vertices, { stroke: "red" }),
// original values as dots
...values.map((y, x) => circle([x * 10, y], 0.2))
)
)
import { filterFuzzy } from "@thi.ng/transducers";
[...filterFuzzy("ho", ["hello", "hallo", "hey", "heyoka"])]
// ["hello", "hallo", "heyoka"]
[...filterFuzzy("hlo", ["hello", "hallo", "hey", "heyoka"])]
// ["hello", "hallo"]
// works with any array-like values & supports custom key extractors
[...filterFuzzy(
[1, 3],
{ key: (x) => x.tags },
[
{ tags: [1, 2, 3] },
{ tags: [2, 3, 4] },
{ tags: [4, 5, 6] },
{ tags: [1, 3, 6] }
]
)]
// [ { tags: [ 1, 2, 3 ] }, { tags: [ 1, 3, 6 ] } ]
import { frequencies, map, reduce, transduce } from "@thi.ng/transducers";
// use the `frequencies` reducer to create
// a map counting occurrence of each value
transduce(map((x) => x.toUpperCase()), frequencies(), "hello world");
// Map { 'H' => 1, 'E' => 1, 'L' => 3, 'O' => 2, ' ' => 1, 'W' => 1, 'R' => 1, 'D' => 1 }
// reduction only (no transform)
reduce(frequencies(), [1, 1, 1, 2, 3, 4, 4]);
// Map { 1 => 3, 2 => 1, 3 => 1, 4 => 2 }
// direct reduction if input is given
frequencies([1, 1, 1, 2, 3, 4, 4]);
// Map { 1 => 3, 2 => 1, 3 => 1, 4 => 2 }
// with optional key function, here to bin by word length
frequencies(
(x) => x.length,
"my camel is collapsing and needs some water".split(" ")
);
// Map { 2 => 2, 5 => 3, 10 => 1, 3 => 1, 4 => 1 }
import { groupByMap } from "@thi.ng/transducers";
// actual grouping (here: by word length)
groupByMap(
{ key: (x) => x.length },
"my camel is collapsing and needs some water".split(" ")
);
// Map {
// 2 => [ 'my', 'is' ],
// 3 => [ 'and' ],
// 4 => [ 'some' ],
// 5 => [ 'camel', 'needs', 'water' ],
// 10 => [ 'collapsing' ]
// }
import { page, comp, iterator, map, padLast, range } from "@thi.ng/transducers";
// extract only items for given page id & page length
[...page(0, 5, range(12))]
// [ 0, 1, 2, 3, 4 ]
// when composing with other transducers
// it's most efficient to place `page()` early on in the chain
// that way only the page items will be further processed
[...iterator(comp(page(1, 5), map(x => x * 10)), range(12))]
// [ 50, 60, 70, 80, 90 ]
// use `padLast()` to fill up missing values
[...iterator(comp(page(2, 5), padLast(5, "n/a")), range(12))]
// [ 10, 11, 'n/a', 'n/a', 'n/a' ]
// no values produced for invalid pages
[...page(3, 5, range(12))]
// []
multiplex and multiplexObj can be used to transform values in
parallel using the provided transducers (which can be composed as usual)
and results in a tuple or keyed object.
import { map, multiplex, multiplexObj, push, transduce } from "@thi.ng/transducers";
transduce(
multiplex(
map((x) => x.charAt(0)),
map((x) => x.toUpperCase()),
map((x) => x.length)
),
push(),
["Alice", "Bob", "Charlie"]
);
// [ [ "A", "ALICE", 5 ], [ "B", "BOB", 3 ], [ "C", "CHARLIE", 7 ] ]
transduce(
multiplexObj({
initial: map((x) => x.charAt(0)),
name: map((x) => x.toUpperCase()),
len: map((x) => x.length)
}),
push(),
["Alice", "Bob", "Charlie"]
);
// [ { len: 5, name: 'ALICE', initial: 'A' },
// { len: 3, name: 'BOB', initial: 'B' },
// { len: 7, name: 'CHARLIE', initial: 'C' } ]
import { comp, map, mean, partition, push, reduce transduce } from "@thi.ng/transducers";
// use nested reduce to compute window averages
transduce(
comp(
partition(5, 1),
map(x => reduce(mean(), x))
),
push(),
[1, 2, 3, 3, 4, 5, 5, 6, 7, 8, 8, 9, 10]
)
// [ 2.6, 3.4, 4, 4.6, 5.4, 6.2, 6.8, 7.6, 8.4 ]
This combined transducer is also directly available as:
import { movingAverage } from "@thi.ng/transducers";
[...movingAverage(5, [1, 2, 3, 3, 4, 5, 5, 6, 7, 8, 8, 9, 10])]
// [ 2.6, 3.4, 4, 4.6, 5.4, 6.2, 6.8, 7.6, 8.4 ]
import { benchmark, mean, repeatedly, transduce } from "@thi.ng/transducers";
// function to test
fn = () => {
let x;
for (i = 0; i < 1e6; i++) {
x = Math.cos(i);
}
return x;
};
// compute the mean of 100 runs
transduce(benchmark(), mean(), repeatedly(fn, 100));
// 1.93 (milliseconds)
import { comp, filter, map, push, trace, transduce } from "@thi.ng/transducers";
// alternatively, use sideEffect() for arbitrary side fx
transduce(
comp(
trace("orig"),
map((x) => x + 1),
trace("mapped"),
filter((x) => (x & 1) > 0)
),
push(),
[1, 2, 3, 4]
);
// orig 1
// mapped 2
// orig 2
// mapped 3
// orig 3
// mapped 4
// orig 4
// mapped 5
// [ 3, 5 ]
The struct transducer is simply a composition of: partitionOf -> partition -> rename -> mapKeys. See code
here.
import { struct } from "@thi.ng/transducers";
// Higher-order transducer to convert linear input into structured objects
// using given field specs and ordering. A single field spec is an array of
// 2 or 3 items: `[name, size, transform?]`. If `transform` is given, it will
// be used to produce the final value for this field. In the example below,
// it is used to unwrap the ID field values, e.g. from `[0] => 0`
[
...struct(
[["id", 1, (id) => id[0]], ["pos", 2], ["vel", 2], ["color", 4]],
[0, 100, 200, -1, 0, 1, 0.5, 0, 1, 1, 0, 0, 5, 4, 0, 0, 1, 1]
)
];
// [ { color: [ 1, 0.5, 0, 1 ],
// vel: [ -1, 0 ],
// pos: [ 100, 200 ],
// id: 0 },
// { color: [ 0, 0, 1, 1 ],
// vel: [ 5, 4 ],
// pos: [ 0, 0 ],
// id: 1 } ]
import { comp, map, mapcat, push, rename, transduce } from "@thi.ng/transducers";
transduce(
comp(
// split into rows
mapcat((x) => x.split("\n")),
// split each row
map((x) => x.split(",")),
// convert each row into object, rename array indices
rename({ id: 0, name: 1, alias: 2, num: "length" })
),
push(),
["100,typescript\n101,clojure,clj\n110,rust,rs"]
);
// [ { num: 2, name: 'typescript', id: '100' },
// { num: 3, alias: 'clj', name: 'clojure', id: '101' },
// { num: 3, alias: 'rs', name: 'rust', id: '110' } ]
import { comp, flatten, push, take, transduce } from "@thi.ng/transducers";
// result is realized after max. 7 values, irrespective of nesting
transduce(comp(flatten(), take(7)), push(), [
1,
[2, [3, 4, [5, 6, [7, 8], 9, [10]]]]
]);
// [1, 2, 3, 4, 5, 6, 7]
import {
comp, count, iterator, map, push, pushCopy, repeat, scan, transduce
} from "@thi.ng/transducers";
// this transducer uses 2 scans (a scan = inner reducer per item)
// 1) counts incoming values
// 2) forms an array of the current counter value `x` & repeated `x` times
// 3) emits results as series of reductions in the outer array produced
// by the main reducer
// IMPORTANT: since arrays are mutable we use `pushCopy` as the inner reducer
// instead of `push` (the outer reducer)
xform = comp(
scan(count()),
map(x => [...repeat(x,x)]),
scan(pushCopy())
)
[...iterator(xform, [1, 1, 1, 1])]
// [ [ [ 1 ] ],
// [ [ 1 ], [ 2, 2 ] ],
// [ [ 1 ], [ 2, 2 ], [ 3, 3, 3 ] ],
// [ [ 1 ], [ 2, 2 ], [ 3, 3, 3 ], [ 4, 4, 4, 4 ] ] ]
// more simple & similar to previous, but without the 2nd xform step
transduce(comp(scan(count()), scan(pushCopy())), push(), [1,1,1,1])
// [ [ 1 ], [ 1, 2 ], [ 1, 2, 3 ], [ 1, 2, 3, 4 ] ]
import { choices, frequencies, take, transduce } from "@thi.ng/transducers";
[...take(10, choices("abcd", [1, 0.5, 0.25, 0.125]))]
// [ 'a', 'a', 'b', 'a', 'a', 'b', 'a', 'c', 'd', 'b' ]
transduce(
take(1000),
frequencies(),
choices("abcd", [1, 0.5, 0.25, 0.125])
);
// Map { 'c' => 132, 'a' => 545, 'b' => 251, 'd' => 72 }
See
tween()
docs for details.
import { tween } from "@thi.ng/transducers";
[
...tween(
10,
0,
100,
(a, b) => [a, b],
([a, b], t) => Math.floor(a + (b - a) * t),
[20, 100],
[50, 200],
[80, 0]
)
];
// [ 100, 100, 100, 133, 166, 200, 133, 66, 0, 0, 0 ]
Apart from type aliases, the only real types defined are:
Reducers are the core building blocks of transducers. Unlike other
implementations using OOP approaches, a Reducer in this lib is a
simple 3-element array of functions, each addressing a separate
processing step.
Since v0.6.0 the bundled reducers are all wrapped in functions to provide a uniform API (and some of them can be preconfigured and/or are stateful closures). However, it's fine to define stateless reducers as constant arrays.
interface Reducer<A, B> extends Array<any> {
/**
* Initialization, e.g. to provide a suitable accumulator value,
* only called when no initial accumulator has been provided by user.
*/
[0]: () => A;
/**
* Completion. When called usually just returns `acc`, but stateful
* transformers should flush/apply their outstanding results.
*/
[1]: (acc: A) => A;
/**
* Reduction step. Combines new input with accumulator.
* If reduction should terminate early, wrap result via `reduced()`
*/
[2]: (acc: A, x: B) => A | Reduced<A>;
}
// A concrete example:
const push: Reducer<any[], any> = [
// init
() => [],
// completion (nothing to do in this case)
(acc) => acc,
// step
(acc, x) => (acc.push(x), acc)
];
partition, partitionBy, streamSort, streamShuffle are (examples
of) transducers making use of their 1-arity completing function.
import type { IDeref } from "@thi.ng/api";
class Reduced<T> implements IDeref<T> {
protected value: T;
constructor(val: T);
deref(): T;
}
Simple type wrapper to identify early termination of a reducer. Does not
modify wrapped value by injecting magic properties. Instances can be
created via reduced(x) and handled via these helper functions:
reduced(x: any): anyisReduced(x: any): booleanensureReduced(x: any): Reduced<any>unreduced(x: any): anyBy default reduce() consumes inputs via the standard ES6 Iterable
interface, i.e. using a for..of.. loop, but uses optimized routes
for some types: Array-like inputs are consumed via a traditional
for-loop and custom optimized iterations can be provided via
implementations of the IReducible interface in the source collection
type. Examples can be found here:
Note: The IReducible interface is only used by reduce(),
transduce() and run().
From Rich Hickey's original definition:
A transducer is a transformation from one reducing function to another
As shown in the examples above, transducers can be dynamically composed
(using comp()) to form arbitrary data transformation pipelines without
causing large overheads for intermediate collections.
type Transducer<A, B> = (rfn: Reducer<any, B>) => Reducer<any, A>;
// concrete example of stateless transducer (expanded for clarity)
function map<A, B>(fn: (x: A) => B): Transducer<A, B> {
return (rfn: Reducer<any, B>) => {
return [
() => rfn[0](),
(acc) => rfn[1](acc),
(acc, x: A) => rfn[2](acc, fn(x))
];
};
}
// stateful transducer
// removes successive value repetitions
function dedupe<T>(): Transducer<T, T> {
return (rfn: Reducer<any, T>) => {
// state initialization
let prev = {};
return [
() => rfn[0](),
(acc) => rfn[1](acc),
(acc, x) => {
acc = prev === x ? acc : rfn[2](acc, x);
prev = x;
return acc;
}
];
};
}
Interface for types able to provide some internal functionality (or
derive some related transformation) as Transducer. Implementations of
this interface can be directly passed to all functions in this package
where a Transducer arg is expected.
import { map, push, range, transduce, type IXform } from "@thi.ng/transducers";
class Mul implements IXform<number, number> {
constructor(public factor = 10) {}
xform() {
return map((x) => this.factor * x);
}
}
transduce(new Mul(11), push(), range(4))
// [0, 11, 22, 33, 44]
import { comp, drop, push, range, takeNth, transduce } from "@thi.ng/transducers";
// also usable w/ comp(), iterator(), step(), run() etc.
transduce(
comp(drop(1), new Mul(11), takeNth(2)),
push(),
range(4)
)
// [11, 33]
comp(f1, f2, ...)
Returns new transducer composed from given transducers. Data flow is from left to right. Offers fast paths for up to 10 args. If more are given, composition is done dynamically via for loop.
compR(rfn: Reducer<any, any>, fn: (acc, x) => any): Reducer<any, any>
Helper function to compose reducers.
iterator<A, B>(tx: Transducer<A, B>, xs: Iterable<A>): IterableIterator<B>
Similar to transduce(), but emits results as ES6 iterator (and hence
doesn't use a reduction function).
reduce<A, B>(rfn: Reducer<A, B>, acc?: A, xs: Iterable<B>): A
Reduces xs using given reducer and optional initial
accumulator/result. If xs implements the IReducible interface,
delegates to that implementation. Likewise, uses a fast route if xs is
an ArrayLike type.
reduceRight<A, B>(rfn: Reducer<A, B>, acc?: A, xs: ArrayLike<B>): A
Similar to reduce, however only accepts ArrayLike sources and reduces them
into right-to-left order.
transduce<A, B, C>(tx: Transducer<A, B>, rfn: Reducer<C, B>, acc?: C, xs: Iterable<A>): C
Transforms iterable using given transducer and combines results with given reducer and optional initial accumulator/result.
transduceRight<A, B, C>(tx: Transducer<A, B>, rfn: Reducer<C, B>, acc?: C, xs: ArrayLike<A>): C
Similar to transduce, however only accepts ArrayLike sources and processes
them into right-to-left order.
run<A, B>(tx: Transducer<A, B>, fx: (x: B) => void, xs: Iterable<A>)
Transforms iterable with given transducer and optional side effect
without any reduction step. If fx is given it will be called with
every value produced by the transducer. If fx is not given, the
transducer is assumed to include at least one sideEffect() step
itself. Returns nothing.
consume(src: Iterable<any>): void
Similar to run(), consumes given iterable, presumably for any implicit
side-effects. Iterable MUST be finite!
import { consume, repeatedly2d } from "@thi.ng/transducers";
// here the function given to repeatedly2d() has only a side-effect, however
// repeatedly2d() itself is lazy. Using consume() then forces this lazy iterator/generator
// to be realized and so also the side-effects to be executed
consume(repeatedly2d((x, y) => console.log("output:", [x, y]), 2, 3));
// output: [ 0, 0 ]
// output: [ 1, 0 ]
// output: [ 0, 1 ]
// output: [ 1, 1 ]
// output: [ 0, 2 ]
// output: [ 1, 2 ]
All of the following functions can be used and composed as transducers. With a few exceptions, most also accept an input iterable and then directly yield a transforming iterator, e.g.
import { map, push, range, transduce } from "@thi.ng/transducers";
// as transducer
transduce(map((x) => x*10), push(), range(4))
// [ 0, 10, 20, 30 ]
// as transforming iterator
[...map((x) => x*10, range(4))]
// [ 0, 10, 20, 30 ]
As with transducer functions, reducer functions can also given an
optional input iterable. If done so, the function will consume the input
and return a reduced result (as if it would be called via reduce()).
If this project contributes to an academic publication, please cite it as:
@misc{thing-transducers,
title = "@thi.ng/transducers",
author = "Karsten Schmidt and others",
note = "https://thi.ng/transducers",
year = 2016
}
© 2016 - 2024 Karsten Schmidt // Apache License 2.0
FAQs
Collection of ~170 lightweight, composable transducers, reducers, generators, iterators for functional data transformations
The npm package @thi.ng/transducers receives a total of 8,016 weekly downloads. As such, @thi.ng/transducers popularity was classified as popular.
We found that @thi.ng/transducers demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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