7MASTERS Programação Funcional - Javascript Funcional Com Ramda

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ANA LUIZA BASTOS github.com/anabastos @naluhh @anapbastos Software Developer na Quanto e cientista da computação na PUC-SP anabastos.me

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JAVASCRIPT FUNCIONAL COM RAMDA

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JS pode ser usado como uma linguagem funcional?

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Javascript tem funções de primeira ordem (HOF)

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Quando falamos de funcional nessas linguagens falamos de “Mantenabilidade” “Menos bugs” “Declaratividade”

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JS vem aos poucos adotando elementos de linguagens funcionais

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PROPOSALS

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Flatmap Partial Application Pipeline operator Pattern Matching

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RAMDA

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Biblioteca que foi pensada para tornar mais fácil o javascript funcional

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● 100% imutável ● ganho em performance ● legibilidade ● point-free / tacit programming

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● Lists(map, filter, reduce, contains, replace, passAll, crop, flatten, find) ● Maths(inc, add, mean, sum) ● String(split, replace) ● Logics(equals, cond, not) ● Relation(intersection, clamp, gt, lt) ● Functions(curry, pipe, compose, ifElse, etc)

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TODAS AS FUNÇÕES SÃO CURRIED

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const add = (x, y) => x + y add(1, 2); // 3 add(1) // Error

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const add = x => y => x + y add(1, 2); // 3 add(1) // Function

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R.add(1, 2); // 3 R.add(1) // Function

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CURRY (PROPOSAL PARTIAL APPLICATION)

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const curryAdd = R.curry((x, y) => x + y)) curryAdd(1, 2); // 3 curryAdd(1)(2); // 3

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PIPE / COMPOSE (PROPOSAL PIPELINE OPERATOR)

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PIPE / COMPOSE: compõe funções de forma sequencial function1 function2 INPUT OUTPUT

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EXEMPLINHO

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Happy Hour: ● Soma o consumido ● Adiciona os 10% ● Divide entre os colegas

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const conta = [9, 9, 9, 9, 15]

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const divideConta = R.pipe( R.sum, // 51 R.mul(1.1), // 56,1 R.divide(6) // 9,35 ) divideConta(conta)

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PIPE COMPOSE

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const ListOfItems = R.compose( Box, List, ListItems )([{...}, {...}, {...}])

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PIPEP / COMPOSEP

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then().then().then().then()

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const asyncStuff = R.pipeP( getId, getUserById, asyncStuff ) // Promise

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IFELSE (maybe monad)

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const findName = R.ifElse( R.has('name'), R.prop('name'), R.always('no name'), )({ id: 123, name: “ana”}) // “ana”

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FLATTER (PROPOSAL FLATMAP)

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R.flatten([1, 2, [3, 4], 5, [6, [7, 8, [9, 12]]]]); // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]

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DATA HANDLING

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EVOLVE

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{ name: “Ana” email: “HELLO@ANABASTOS.ME”, phone: “11 98698-3010”, address: “rua da aparecida 304 apt34 ”, }

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R.evolve({ email: R.toLower, phone: R.replace(‘-’, ‘’), })(data) // { // name: “Ana” // email: “hello@anabastos.me”, // phone: “11 9869983010” // address: ... // }

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APPLY SPEC

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const createObj = R.applySpec({ counter: R.inc, userData: { phone: R.trim}, }) createObj(0, “ 98499-1900”) // {1, userData{ phone: “9849919000”}}

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TryCatch Cond Memoization Lenses

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BOM TOOLBOX

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COOKBOOK

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● Rambda - github.com/selfrefactor/rambda ● Ramda-fantasy - github.com/ramda/ramda-fantasy ● Thinking Ramda - randycoulman.com/blog/2016/05/24/thinking-in-ramda-getting -started ● Ramda - Derek Stavis(Pagar.me talks)

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OBRIGADA :) speakerdeck.com/anabastos anabastos.me github.com/anabastos @naluhh @anapbastos