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+BWB4DSJQU ࣌ʑ5ZQF4DSJQU
Ͱ
ΏΔ͔ʹ͡ΊΔؔܕϓϩάϥϛϯά
Introducing functional programming w/ JavaScript
( & sometimes TypeScript )
ॳՆͷ+BWB4DSJQUࡇ
!XBLBNTIB
/BPLJ:"."%"
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͡Ίʹ
+BWB4DSJQUʹؔܕϓϩάϥϛϯάͷΤοηϯε͕ଟʹؚ·Ε͍ͯΔ
ϦΞΫςΟϒɾϓϩάϥϛϯάͷྲྀߦʹΑΓɺXFCϑϩϯτΤϯυͷੈք
ʹਁಁ͖ͯͨ͠
ͦΜͳؔܕϓϩάϥϛϯάͷ͞ΘΓ෦Λ͝հ
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·ͣͪ͜ΒͷίʔυΛޚཡ͍ͩ͘͞
First, please take a look at this code…
TS
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['foo', 'bar', 'baz'].map((val: string) => {
return `${val}!!!`;
});
//=> ['foo!!!', 'bar!!!', 'baz!!!']
function double(x: number): number {
return x * 2;
}
double(3); //=> 6
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['foo', 'bar', 'baz'].map((val: string) => {
return `${val}!!!`;
});
//=> ['foo!!!', 'bar!!!', 'baz!!!']
function double(x: number): number {
return x * 2;
}
double(3); //=> 6
ͲͪΒؔܕϓϩάϥϛϯάͷఆٛʹଈͨ͠ͷͰ͢
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['foo', 'bar', 'baz'].map((val: string) => {
return `${val}!!!`;
});
//=> ['foo!!!', 'bar!!!', 'baz!!!']
function double(x: number): number {
return x * 2;
}
double(3); //=> 6
ͦͦؔܕϓϩάϥϛϯάͱʁ
ෳͷࣜΛؔͷద༻ʹΑͬͯΈ߹ΘͤΔϓϩάϥϛϯάελΠϧ
ؔ߹
෭࡞༻ͷແ͍ؔΛϝΠϯʹѻ͏ϓϩάϥϛϯάελΠϧ
७ਮ
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['foo', 'bar', 'baz'].map((val: string) => {
return `${val}!!!`;
});
//=> ['foo!!!', 'bar!!!', 'baz!!!']
function double(x: number): number {
return x * 2;
}
double(3); //=> 6
ରٛʹҐஔ͢Δͷ͕ʰखଓ͖ܕϓϩάϥϛϯάʱ
มΛഁյతʹॻ͖͑ΔͳͲɺ෭࡞༻Λۦ͢Δ
తͷͨΊʹ࣮ߦ͖͢Ұ࿈ͷεςοϓΛҰͭͷؔʹ࣋ͨͤΔ
ఆٛͨؔ͠ϓϩάϥϜ࣮ߦதͷҙͷλΠϛϯάͰݺͼग़ͤΔ
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ؔ߹
খ͞ͳؔΛΈ߹ΘͤΔͱ͍͏͜ͱ
ߴ֊ؔ
७ਮ
෭࡞༻Λແ͘͢ͱ͍͏͜ͱ
ෆมੑ *NNVUBCMF
ࢀরಁաੑ
͜Ε͔ΒؔܕϓϩάϥϛϯάΛֶͿਓ
ຊ͓࣋ͪؼΓ͍͖͍ͨͩͨ͜ͱ
1PJOUTUP
MFBSO
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ؔ߹
ෳͷࣜΛؔͷద༻ʹΑͬͯΈ߹ΘͤΔϓϩάϥϛϯάελΠϧ
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ͱɺͦͷલʹߴ֊ؔʹ͍ͭͯ
About a higher-order function
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ͱɺͦͷલʹߴ֊ؔʹ͍ͭͯ
[1, 4, 9, 16].map(x => x * 2);
['spray', 'limit', 'exuberant', 'present'].filter(word =>
word.length > 6
);
"SSBZͷ*UFSBUJWFͳϝιουؔΛҾʹऔΔ
ؔΛҾPSΓͱͯ͠ѻ͏ͷΛʰߴ֊ؔʱͱ͍͏
ߴ֊ؔؔΛ߹͢ΔͷͰ͋Δ
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؆୯ͳؔ߹ΛͬͯΈΑ͏
Basic Examples
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/**
* ཁ݅: ͋Δʹ 1 Λͯ͠ 2ഒͨ݁͠ՌΛฦ͢ػೳ
*/
// ҰͭͷؔͰ࣮ݱ͢Δͱ͜͏ͳΔ
// ಛԽ͗ͯͯ͢͠൚༻ੑʹ͚ܽΔͨΊɺอकੑ͍
function addOneTimesTwo(x: number): number {
return (x + 1) * 2;
}
// Ҿʹ 1 Λ͚ͩ͢
function addOne(x: number): number {
return x + 1;
}
// ҾΛ 2ഒ͢Δ͚ͩ
function timesTwo(x: number): number {
return x * 2;
}
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/**
* ཁ݅: ͋Δʹ 1 Λͯ͠ 2ഒͨ݁͠ՌΛฦ͢ػೳ
*/
// ݁Ռશͯಉ͡
addOneTimesTwo(2); //=> 6
const x = addOne(2);
timesTwo(x); //=> 6
timesTwo(addOne(2)); //=> 6
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DPNQPTF߹༻ͷؔΛ࡞ͬͯΈΑ͏
Basic Examples
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function compose(fn1, fn2) {
return function(x0) {
return fn1(fn2(x0));
}
}
// TypeScript Ͱॻ͘ͱ͜Μͳײ͡
function compose(
fn1: (x: T1) => T2,
fn2: (x0: V0) => T1,
): (x0: V0) => T2 {
return function(x0: V0): T2 {
return fn1(fn2(x0));
};
}
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const addOneTimesTwo = compose(timesTwo, addOne);
addOneTimesTwo(2);
//=> 6
compose(timesTwo, addOne)(2);
//=> 6
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const addOneTimesTwo = compose(timesTwo, addOne);
addOneTimesTwo(2);
//=> 6
compose(timesTwo, addOne)(2);
//=> 6
ؔ߹
ؔͻͱ·ͱ·Γʹͤͣɺࡉ͔͘ղ͢Δ
খ͞ͳؔΛΈ߹Θͤͯେ͖ͳػೳΛ࣮ݱ͢Δ
খ͘͞୯७ͳؔɺͦΕ͚ͩ൚༻ੑ͕ߴ͍
6OJU5FTUΛॻ͘ͷ͕༰қʹͳΔ
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७ਮ
෭࡞༻ͷͳ͍ؔΛϝΠϯʹѻ͏ϓϩάϥϛϯάελΠϧ
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·ͣͪ͜ΒͷίʔυΛޚཡ͍ͩ͘͞
First, please take a look at this code…
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// 1
function sum(x: number, y: number): number {
return x + y;
}
// 2
let i: number = 0;
function sum2(x: number, y: number): number {
i += x + y;
return x + y;
}
// 3
function sum3(x: number, y: number): number {
return x + y + i;
}
// 4
function sum4(x: number, y: number): number {
const result = x + y;
console.log(result);
return result;
}
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// 1
function sum(x: number, y: number): number {
return x + y;
}
// 2
let i: number = 0;
function sum2(x: number, y: number): number {
i += x + y;
return x + y;
}
// 3
function sum3(x: number, y: number): number {
return x + y + i;
}
// 4
function sum4(x: number, y: number): number {
const result = x + y;
console.log(result);
return result;
}
Ұ͚͕ͭͩ७ਮͳؔͰ͢
ଞશͯʰෆ७ʱͳؔͰ͢
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// 1
function sum(x: number, y: number): number {
return x + y;
}
// 2
let i: number = 0;
function sum2(x: number, y: number): number {
i += x + y;
return x + y;
}
// 3
function sum3(x: number, y: number): number {
return x + y + i;
}
// 4
function sum4(x: number, y: number): number {
const result = x + y;
console.log(result);
return result;
}
७ਮͳؔͱ
ΓඞͣҾͱͯ͠༩͑ΒΕ͔ͨΒͷΈܭࢉ͞ΕΔ
ؔͷ֎෦Ͱมߋ͞ΕΔՄೳੑͷ͋ΔσʔλʹҰґଘ͠ͳ͍
࣮ؔߦ෦ͷ֎ଆʹଘࡏ͢ΔԿ͔͠Βͷঢ়ଶΛҰมߋ͠ͳ͍
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// ҾͷΛ͠ࢉ͚ͨͩ͠ ( ७ਮ )
function sum(x: number, y: number): number {
return x + y;
}
// άϩʔόϧมΛมߋ͍ͯ͠Δ
let i: number = 0;
function sum2(x: number, y: number): number {
i += x + y;
return x + y;
}
// Γ͕Ҿ͚ͩ͡Όͳ͘άϩʔόϧมʹґଘͯ͠Δ
function sum3(x: number, y: number): number {
return x + y + i;
}
// console.log ͱ͍͏શʹ֎ͷੈքʹׯবͯ͠Δ
function sum4(x: number, y: number): number {
const result = x + y;
console.log(result);
return result;
}
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෭࡞༻ͳΔ͘ແ͍ํ͕·͍͠
ঢ়ଶΛؔͨ͠ґଘ͕ؔੜ·Εͯ͠·͏
ঢ়ଶͱάϩʔόϧมΠϯελϯεͳͲ
ґଘؔͱؔͷݺͼग़͠ॱংͳͲ
࠶ݱੑʹ੍͕ൃੜ͢Δ
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෭࡞༻Λແͨ͘͢ΊͷୈҰา
The first step to eliminate side effects…
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෭࡞༻Λແͨ͘͢ΊͷୈҰา
let i: number = 0;
function sum3(x: number, y: number, i: number): number {
return x + y + i;
}
ॲཧʹඞཁͳσʔλશͯҾͱͯ͠ड͚औΔ
άϩʔόϧมҾͱͯ͠ड͚औΕ0,
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interface User {
firstName: string;
lastName: string;
greet(): string;
}
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class User {
constructor(private firstName: string, private lastName: string) {}
public updateFirstName(name: string): User {
return new User(name, this.lastName);
}
public updateLastName(name: string): User {
return new User(this.firstName, name);
}
public greet(): string {
return `hello, ${this.firstName} ${this.lastName}!!`;
}
}
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class User {
constructor(private firstName: string, private lastName: string) {}
public updateFirstName(name: string): User {
return new User(name, this.lastName);
}
public updateLastName(name: string): User {
return new User(this.firstName, name);
}
public greet(): string {
return `hello, ${this.firstName} ${this.lastName}!!`;
}
}
ΦϒδΣΫτ$MBTTͱͯ͠ఆٛ͢Δ
֤ϝιουͷ࠷ޙʹࣗͷ৽͍͠ΠϯελϯεΛΓʹฦ͢
ຖճ৽͍͠ΠϯελϯεΛͦͷ࣌ͷ෦͔Βੜ͢Δ
ݺͼग़͠ͷίϯϑϦΫτ͕ൃੜ͠ͳ͍
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ࢀরಁաੑ
ؔΛͦͷΓࣗମʹࠩ͠ସ͑ͯϓϩάϥϜશମ͕յΕͳ͍͜ͱ
ຊͷࠃձຊͷटͰ։͔ΕΔ
ຊͷࠃձ౦ژͰ։͔ΕΔ
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७ਮ
ґଘؔΛ࣋ͨͳ͍ͱ͍͏͜ͱɺͦΕ͚ͩίʔυͷݟ௨͕͠ྑ͍
ݟ௨͠ͷྑ͍ίʔυอकੑ͕ߴ͍
ґଘؔΛ࣋ͨͳ͍७ਮؔ6OJU5FTU͕͍͢͠
6OJU5FTUͷ͍͢͠ίʔυอकੑ͕ߴ͍
७ਮؔ߹͕͍͢͠
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3BNEBKT
ڧྗͳؔܕϓϩάϥϛϯά༻ JavaScript ϥΠϒϥϦ
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3BNEBKT
ίϨΫγϣϯૢ࡞ܥͱෆมੑ୲อ ७ਮ
ͷೋ໘ੑΛซͤ࣋ͭ
΄΅શͯͷ"1*ෆมੑͱ෭࡞༻ͷͳ͍ػೳ *NNVUBCMF
ͱͯ͠ઃܭ
"1*໊͕)BTLFMM4DBMBͷͦΕʹΠϯεύΠΞ͞Ε໋໊ͨ
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PSYENCE:MEDIA
PRODUCED BY
ৄ͘͠ฐࣾϒϩάΛ͝ࢀর͍ͩ͘͞
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ؔܕϓϩάϥϛϯάͷϝϦοτσϝϦοτ
First, please take a look at this code…
TS
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ؔܕϓϩάϥϛϯάͷϝϦοτ
ҰͭҰͭͷ෦ ؔ
͕খ͍͞ͷͰอकੑɾ֦ுੑ͕ߴ͍
6OJU5FTU͕ॻ͖͍͢
ґଘؔͰ಄Λ·͢͜ͱ͕গͳ͍
෭࡞༻Λ͍ग़͢͜ͱͰ༧ظͤ͵ಈ࡞ ෆ۩߹
Λະવʹ͛Δ
TS
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ؔܕϓϩάϥϛϯάͷϝϦοτ
Ұൠతͳ(6*ΞϓϦέʔγϣϯͱͷ૬ੑ͕ྑ͍
ϦΞΫςΟϒϓϩάϥϛϯά 3Y'MVYͳͲ
͕ద͍ͯ͠Δ
TS
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ؔܕϓϩάϥϛϯάͷσϝϦοτ
߽ϓϩάϥϛϯάʹͳΓ͕ͪ
ඞવతʹؔͷݺͼग़͠ճ͕૿͑Δ ؔ߹ͳͲ
ֶशίετ͕ߴ͍
खଓ͖ܕͱύϥμΠϜ͕ͥΜͥ̽ҧ͏
TS
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͜Ε͔ΒؔܕϓϩάϥϛϯάΛֶͿਓ
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͜Ε͔ΒؔܕϓϩάϥϛϯάΛֶͿਓ
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͜Ε͔ΒؔܕϓϩάϥϛϯάΛֶͿਓ
ʰ1BSTFSΛ࡞ͬͯΈΔʱ͕ࡐͱ͓ͯ͢͢͠Ί
దͳ+40/σʔλΛߏղੳͯ͠ΈΔͱ͔
؆୯ͳίʔυϑΥʔϚολΛ࡞ͬͯΈΔͱ͔
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͜Ε͔ΒؔܕϓϩάϥϛϯάΛֶͿਓ
ຊ֨తʹֶͼ͍ͨͳΒ)BTLFMM
ਖ਼ਅਖ਼ͷʰ७ਮؔܕϓϩάϥϛϯάݴޠʱ
੩తܕ͚ݴޠ
XFCܥͷۀʹ݁͢Δ͜ͱগͳ͍͕ɺʰڭཆʱͱͯ͠
ֶͿͳΒ͜Ε͕࠷ద
ʰ͍͢͝)ຊʱҰࣸܦ͢Δ͚ͩͰ͔ͳΓͷֶͼʹͳΔ
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*OUSPEVDFNZTFMG
Զͷ໊ΛݴͬͯΈΖ
ࣗݾհ
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!XBLBNTIB
*OUSPEVDFNZTFMG
/BPLJ:"."%"ࢁాथ
XFCϑϩϯτΤϯυΤϯδχΞ
ॴଐגࣜձࣾϦΫϧʔτϚʔέςΟϯάύʔτφʔζ
෭ۀۀҕୗͱͯ͠ελʔτΞοϓاۀΛ͓ख͍த
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PSYENCE:MEDIA
PRODUCED BY
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PSYENCE:MEDIA
PRODUCED BY
ϦΫϧʔτϚʔέςΟϯάύʔτφʔζͷެࣜςοΫϒϩά
ٕज़ྗɾϊϋͷମܥԽ
3.1ͷ։ൃ৫͓Αͼࣥචऀͷࣾ֎ϓϨθϯε্
࠾༻ϒϥϯσΟϯάڧԽ
ۀք׆ੑԽͷߩݙ
14:&/$&.&%*"
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No content
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https://tech.recruit-mp.co.jp
3.1 ϒϩά
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5IBOLZPV