transducer

Transducer flatten and uniq

由 ￡可爱￡侵袭症＋ 提交于 2021-02-04 20:58:49
问题 I'm wondering if there is a way by using a transducer for flattening a list and filter on unique values? By chaining, it is very easy: import {uniq, flattenDeep} from 'lodash';| const arr = [1, 2, [2, 3], [1, [4, 5]]]; uniq(flattendDeep(arr)); // -> [1, 2, 3, 4, 5] <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.core.min.js"></script> But here we loop twice over the list (+ n by depth layer). Not ideal. What I'm trying to achieve is to use a transducer for this

Transducer flatten and uniq

由 戏子无情 提交于 2021-02-04 20:58:26
问题 I'm wondering if there is a way by using a transducer for flattening a list and filter on unique values? By chaining, it is very easy: import {uniq, flattenDeep} from 'lodash';| const arr = [1, 2, [2, 3], [1, [4, 5]]]; uniq(flattendDeep(arr)); // -> [1, 2, 3, 4, 5] <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.core.min.js"></script> But here we loop twice over the list (+ n by depth layer). Not ideal. What I'm trying to achieve is to use a transducer for this

Transducer flatten and uniq

由 妖精的绣舞 提交于 2021-02-04 20:58:16
问题 I'm wondering if there is a way by using a transducer for flattening a list and filter on unique values? By chaining, it is very easy: import {uniq, flattenDeep} from 'lodash';| const arr = [1, 2, [2, 3], [1, [4, 5]]]; uniq(flattendDeep(arr)); // -> [1, 2, 3, 4, 5] <script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.core.min.js"></script> But here we loop twice over the list (+ n by depth layer). Not ideal. What I'm trying to achieve is to use a transducer for this

How to functional compose transforms of objects via transducers

由 江枫思渺然 提交于 2020-01-02 14:32:15
问题 Live code example I'm trying to learn transducers via egghead and I think I got it until we try to compose object transformation. I have an example below that doesn't work const flip = map(([k,v]) => ({[v]: k})); const double = map(([k,v]) => ({[k]: v + v})); seq(flip, {one: 1, two: 2}); /*?*/ {1: 'one', 2: 'two'} seq(double, {one: 1, two: 2}); /*?*/ {'one': 2, 'two: 4} but if I compose it fails: seq(compose(flip, double), {one: 1, two: 2}); /*?*/ {undefined: NaN} seq(compose(double, flip),

How to functional compose transforms of objects via transducers

由 旧城冷巷雨未停 提交于 2020-01-02 14:31:23
问题 Live code example I'm trying to learn transducers via egghead and I think I got it until we try to compose object transformation. I have an example below that doesn't work const flip = map(([k,v]) => ({[v]: k})); const double = map(([k,v]) => ({[k]: v + v})); seq(flip, {one: 1, two: 2}); /*?*/ {1: 'one', 2: 'two'} seq(double, {one: 1, two: 2}); /*?*/ {'one': 2, 'two: 4} but if I compose it fails: seq(compose(flip, double), {one: 1, two: 2}); /*?*/ {undefined: NaN} seq(compose(double, flip),

Parsing either font style or block of paragraph in GATE

由 半腔热情 提交于 2019-12-24 12:47:13
问题 I have a word document. I need to match particular table section or heading section of it using GATE. I thought if there were any steps from where we can first check any font size or font style of the heading and then match rest of the content till next heading pattern repeats. 回答1: GATE has only a limited support for MS Word documents provided by the Apache Tika and Apache POI libraries. I do not know about any free alternative... We have developed our own plugin ( gate.DocumentFormat ) for

How to avoid intermediate results when performing array iterations?

由 混江龙づ霸主 提交于 2019-12-22 12:38:30
问题 When working with arrays, intermediate representations are needed regularly - particularly in connection with functional programming, in which data is often treated as immutable: const square = x => x * x; const odd = x => (x & 1) === 1; let xs = [1,2,3,4,5,6,7,8,9]; // unnecessary intermediate array: xs.map(square).filter(odd); // [1,4,9,16,25,36,49,64,81] => [1,9,25,49,81] // even worse: xs.map(square).filter(odd).slice(0, 2); // [1,9] How can I avoid this behavior in Javascript/Ecmascript

function composition with rest operator, reducer and mapper

由 瘦欲@ 提交于 2019-12-11 07:09:12
问题 I'm following an article about Transducers in JavaScript, and in particular I have defined the following functions const reducer = (acc, val) => acc.concat([val]); const reduceWith = (reducer, seed, iterable) => { let accumulation = seed; for (const value of iterable) { accumulation = reducer(accumulation, value); } return accumulation; } const map = fn => reducer => (acc, val) => reducer(acc, fn(val)); const sumOf = (acc, val) => acc + val; const power = (base, exponent) => Math.pow(base,

Transducers in Haskell and the monomorphism restriction

由 别说谁变了你拦得住时间么 提交于 2019-12-08 20:36:18
问题 I implemented transducers in Haskell as follows: {-# LANGUAGE RankNTypes #-} import Prelude hiding (foldr) import Data.Foldable type Reducer b a = a -> b -> b type Transducer a b = forall t. Reducer t b -> Reducer t a class Foldable c => Collection c where insert :: a -> c a -> c a empty :: c a reduce :: Collection c => Transducer a b -> c a -> c b reduce f = foldr (f insert) empty mapping :: (a -> b) -> Transducer a b mapping f g x = g (f x) Now I want to define a generic map function. Hence

How to functional compose transforms of objects via transducers

由 微笑、不失礼 提交于 2019-12-06 06:22:47
Live code example I'm trying to learn transducers via egghead and I think I got it until we try to compose object transformation. I have an example below that doesn't work const flip = map(([k,v]) => ({[v]: k})); const double = map(([k,v]) => ({[k]: v + v})); seq(flip, {one: 1, two: 2}); /*?*/ {1: 'one', 2: 'two'} seq(double, {one: 1, two: 2}); /*?*/ {'one': 2, 'two: 4} but if I compose it fails: seq(compose(flip, double), {one: 1, two: 2}); /*?*/ {undefined: NaN} seq(compose(double, flip), {one: 1, two: 2}); /*?*/ {undefined: undefined} How can I work with objects using transducers with fp
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