Please why is my code not working,do I need to install any library

Question

Recently started functional programming and all explanations of the pipe and compose using reduce which I have seen are very sketchy.


const x = 4

const add2 = x + 2

const multiplyBy5 = x * 5

const subtract1 = x - 1



pipe = (...functions) =>
(x) => functions.reduce((v, function) => function(v), x)

const result = pipe(add2, multiplyBy5, subtract1)(4)
console.log(result)

Try adding ";" at the end of every line. Since this is javascript, you need to add it. I am not sure if this will fix your problem, but it is an error. — FairOPShotgun, May 14 '22 at 22:58
@FairOPShotgun semicolons are not necessary except in certain ambiguous situations. see: [What are the rules for JavaScript's automatic semicolon insertion (ASI)?](https://stackoverflow.com/questions/2846283/what-are-the-rules-for-javascripts-automatic-semicolon-insertion-asi) — pilchard, May 14 '22 at 23:08

score 3 · Answer 1 · answered May 14 '22 at 23:11

3

There were 2 errors.

The first one was that the x, add2, multiplyBy5 and subtract1 were not functions, but mere definitions.
The other was that you naming a variable (using the arguments) to a name that is a "reserved" word such as "function" did break the syntax parser.

const x = (x) => x
const add2 = (x) => x+2
const multiplyBy5 = (x) => x*5
const subtract1 = (x) => x-1

const pipe = (...functions) => (x) => functions.reduce((v,fn)=>fn(v),x)
const result = pipe(
  add2,
  multiplyBy5,
  subtract1,
)(4);
console.log(result)

answered May 14 '22 at 23:11

Akxe

9,694
3
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71

1

Btw, we can leave the first one as the definition :) – Maharramoff May 14 '22 at 23:17
Thanks a lot.What is most annoying is that ,the initial code I wrote with the whole fns and fn started working.It was showing an error ,the reason I changed it but right now it is working – Steve purpose May 15 '22 at 06:15

score 0 · Answer 2 · answered May 14 '22 at 23:12

I think it should be done like this:

const add2 = (x) => x+2
    
const multiplyBy5 = (x) => x*5
    
const subtract1 = (x) => x-1
    
const pipe=(...functions) => (x) => functions.reduce((v, functionA) => functionA(v), x)
    
const result=pipe(add2, multiplyBy5, subtract1)(4)
    
console.log(result)

Please why is my code not working,do I need to install any library

2 Answers2