ramda/ramda

Practical functional Javascript

Kevin Thompson

@kthompson

im trying to make a method to convert a list into a map by id with rambda, i have the follow following but its not working as expected:

const assignById = converge(call, [
  flip(assoc),
  prop('id')
]);

assignById({id: 'abc', taco: 'time'}, {}) // => {abc: {id: 'abc', taco: 'time'} }

Kevin Thompson

@kthompson

i think this will work for now

const toMap = R.pipe(
  R.groupBy(R.prop('id')),
  R.map(R.head)
)

Brad Compton (he/him)

@Bradcomp

converge sets its arity based on the highest arity of the branch functions

Kevin Thompson

@kthompson

yea i was reading that but still couldnt really figure it out

Brad Compton (he/him)

@Bradcomp

Since assoc has an arity of 3 it will take all 3 arguments before passing the results to call

if you need to partially apply a function in converge you can either do it manually (x) => flip(assoc)(x) or use a helper function like arity

Kevin Thompson

@kthompson

i dont see arity but thanks for the info

Brad Compton (he/him)

@Bradcomp

Sorry, it's called nAry

arity seems like a more reasonable name lol

Kevin Thompson

@kthompson

Yea. That gives me something like

const toMap2 = R.reduce(
  R.flip(
    R.uncurryN(
      2, 
      R.converge(R.call, [
        x => R.flip(R.assoc)(x),
        R.prop('id')
      ])
    )
  ), 
  {}
);

i think the other implementation is a bit more clear/concise though

Twizzes

@Twizzes

@kthompson can you use Object.entries?

Kevin Thompson

@kthompson

i'm taking an array of objects and turning it into a map with the object's id as the key.

const toMap = R.pipe(
  R.groupBy(R.prop('id')),
  R.map(R.head)
)

is the simplest way i can come up with

Brad Compton (he/him)

@Bradcomp

i think the other implementation is a bit more clear/concise though

:+1:

Kevin Thompson

@kthompson

Oh, I just found this...

const toMap3 = R.indexBy(R.prop('id'));

mitcho

@mitchoSR_twitter

gotta love that progression haha

Gezim Hoxha

@HappyGezim_twitter

Why does the object in filter (second param) have to have an index type of 'string'?

Lewis

@6ewis

do you have a cleaner alternative

Lewis

@6ewis

const showColumns= (visibleColumns)  =>
  headers.reduce((acc, header) => {
    const indexOfVisibleColumn = visibleColumns.map(col => col.name).indexOf(header.name);
    if ( indexOfVisibleColumn !== -1) {
      const { title } = visibleColumns[indexOfVisibleColumn]
      title  ?
        acc.push({ ...header, title }) :
        acc.push({ ...header })
    }; 

    console.log("how does acc look like", acc);
    return acc;
  }, []); 
;

Twizzes

@Twizzes

@6ewis

const visibleNames = R.map(R.prop('name'))

headers.filter(header => R.includes(R.prop('name')(header), visibleNames(visibleColumns)))

Julien Gonzalez

@customcommander

Is it right/appropriate to have this ramda-adjunct package “advertised" so many times in the Ramda Cookbook? I was tempted to raise a PR to remove this but wanted to check first. Personally I don’t think it is; it causes confusion more than anything.

Julien Gonzalez

@customcommander

I mean isn’t a link in “Related projects” enough?
https://github.com/ramda/ramda/wiki#related-projects

If other projects were doing the same thing, the Cookbook could become a messy place IMHO.

Oscar Bolmsten

@oscar-b

Any @types maintainer here? Either I'm daft or there's missing type for takeLastWhile when used with a string.

Daniel Cheung

@danvim

I just added "rambda": "^4.4.0" to my project. From the docs, I see that it supposedly has the invert and invertObj functions. However, I can't find them in the dist. When I open up src under the node_module, I do see invert and invertObj in their respective files though.

Anyone knows what has happened to them?

Syaiful Bahri

@syaiful6

@danvim i guess it's typo problem, it's ramda not rambda

John Hartnup

@ukslim

rambda is a "faster alternative to Ramda" -- but I don't see anything about invert in its docs: https://selfrefactor.github.io/rambda/#/

I do see invert in Rambda docs's list of "Ramda methods missing in Rambda" - https://github.com/selfrefactor/rambda/blob/master/files/ramdaMissing.md

John Hartnup

@ukslim

Interesting - Rambda's authors say they see the fewer methods as an advantage, and it looks as if they feel the methods they've chosen to omit are ones you're likely not to need. But I see tons of functions that my team uses a lot. converge, applySpec, cond, unless, when ...

Daniel Cheung

@danvim

Thanks, that's interesting. It's my first time using ramda. I used to use lodash. Thought it made sense if the name would contain a 'b', but it didn't.

John Hartnup

@ukslim

Since I've broken my Gitter silence: a plug for the library I recently published - https://www.npmjs.com/package/ramda-decimal#ramda-decimal

Feedback very welcome.

kapilpipaliya

@kapilpipaliya

thanks for ramda

Lewis

@6ewis

R.isNil(a) || R.isNil(b)

Oskar Grunning

@sQVe

What would be the best way to write a signature for a object {k: v} but with a specfic design? It has the name Container in my TypeScript code but I'm a bit unsure how I should write the Hindley Milner signature.

combineContainers :: {k: v} -> {k: v} -> {k: v} seems a bit too generic - or am I wrong?

Brad Compton (he/him)

@Bradcomp

@6ewis any(isNil, [a, b])?

@sQVe is Container like a specific record type, or is it more like a typeclass?

Norbert

@norbertpy

Folks, what stops the 0.27.0 version to be published?

John Hartnup

@ukslim

@6ewis Why do you feel 'shortest' is a useful aim? And why mix Ramda and non-Ramda styles? or(isNil(a), isNil(b))

Mike Lambert

@lambert-velir

hey guys! I had a problem the other day, I needed to include all elements that had the field excluded set to true, but also all the elements that are before for after one that has excluded true

here's some sample data:

[
  {
    id: 1
  },
  {
    id: 2
  },
  {
    id: 3,
    excluded: true
  },
  {
    id: 4,
    excluded: true
  },
  {
    id: 5
  },
  {
    id: 6
  }
];

so the results should be 2, 3, 4, 5

I ended up using a regular [].reduce because I had an index, and could look at i -1 and i + 1

I was thinking about using R.aperture, but it doesn't quite do what I need

essentially, I need a filter that can look at the elements next to it

here's my solution:

array.reduce((acc, d, i) => {
  const excluded = d => d && d.exclude === true;

  if (excluded(d) || excluded(array[i - 1]) || excluded(array[i + 1])) {
    return acc.concat(d);
  }
  else {
    return acc;
  }
}, [])

John Hartnup

@ukslim

I'd be thinking about doing something slightly dirty with addIndex() and peeking into the original array.

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