mapObjIndexedToArray

[srghma]

Is your feature request related to a problem? Please describe.

Function maps object properties into array.

Describe the solution you'd like

// mapObjIndexedToArray: ((v, k, {k: v}) → v') → {k: v} → [v']

/*
* @example
*
*      const xyz = { x: 1, y: 2, z: 3 };
*      const prependKeyAndDouble = (num, key, obj) => key + (num * 2);
*
*      mapObjIndexedToArray(prependKeyAndDouble, xyz); //=> ['x2', 'y4', 'z6']
*/

const mapObjIndexedToArray = curry((fn, obj) => {
  return _map(function(key) {
    return fn(obj[key], key, obj);
  }, keys(obj));
});

Describe alternatives you've considered

// mapObjIndexedToArray: ((v, k, {k: v}) → v') → {k: v} → [v']
const mapObjIndexedToArray = R.curryN(2, (func, obj) =>
  R.compose(
    R.values,
    R.mapObjIndexed(func),
  )(obj),
)

Additional context

const patient = {
  'abbrev@1':{
    version:'1.0.9',
    resolved:'https://registry.yarnpkg.com/abbrev/-/abbrev-1.0.9.tgz#91b4792588a7738c25f35dd6f63752a2f8776135'
  },
  'shell-quote@git+https://github.com/srghma/node-shell-quote.git#without_unlicenced_jsonify':{
    version:'1.6.0',
    resolved:'git+https://github.com/srghma/node-shell-quote.git#0aa381896e0cd7409ead15fd444f225807a61e0a'
  },
  '@graphile/plugin-supporter@git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git':{
    version:'1.6.0',
    resolved:'git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git#1234commit'
  },
}

const result = mapObjIndexedToArray((value, key) => ({ ...value, name: key }), patient)

const expected = [
  {
    name: 'abbrev@1',
    version:'1.0.9',
    resolved:'https://registry.yarnpkg.com/abbrev/-/abbrev-1.0.9.tgz#91b4792588a7738c25f35dd6f63752a2f8776135'
  },
  {
    name: 'shell-quote@git+https://github.com/srghma/node-shell-quote.git#without_unlicenced_jsonify',
    version:'1.6.0',
    resolved:'git+https://github.com/srghma/node-shell-quote.git#0aa381896e0cd7409ead15fd444f225807a61e0a'
  },
  {
    name:   '@graphile/plugin-supporter@git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git',
    version:'1.6.0',
    resolved:'git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git#1234commit'
  },
]

expect(result).toEqual(result)

[char0n]

Can you pls demonstrate some examples on some fixtures data and explain the reason why it should return the array ? I'm trying to understand your motivation and see the practicality of such a function. Thank you

[srghma]

Motivation:

what you can do with it is transform:

const patient = {
  'abbrev@1':{
    version:'1.0.9',
    resolved:'https://registry.yarnpkg.com/abbrev/-/abbrev-1.0.9.tgz#91b4792588a7738c25f35dd6f63752a2f8776135'
  },
  'shell-quote@git+https://github.com/srghma/node-shell-quote.git#without_unlicenced_jsonify':{
    version:'1.6.0',
    resolved:'git+https://github.com/srghma/node-shell-quote.git#0aa381896e0cd7409ead15fd444f225807a61e0a'
  },
  '@graphile/plugin-supporter@git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git':{
    version:'1.6.0',
    resolved:'git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git#1234commit'
  },
}

const result = mapObjIndexedReturnArray((value, key) => ({ ...value, name: key }), patient)

const expected = [
  {
    name: 'abbrev@1',
    version:'1.0.9',
    resolved:'https://registry.yarnpkg.com/abbrev/-/abbrev-1.0.9.tgz#91b4792588a7738c25f35dd6f63752a2f8776135'
  },
  {
    name: 'shell-quote@git+https://github.com/srghma/node-shell-quote.git#without_unlicenced_jsonify',
    version:'1.6.0',
    resolved:'git+https://github.com/srghma/node-shell-quote.git#0aa381896e0cd7409ead15fd444f225807a61e0a'
  },
  {
    name:   '@graphile/plugin-supporter@git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git',
    version:'1.6.0',
    resolved:'git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git#1234commit'
  },
]

expect(result).toEqual(result)

pretty useful function I think, I needed it 3 times in my life

[char0n]

Yeah I see the potential there. We have to be careful with the name though, map invokes homomorphic operation. This is more like unzipObjectWith/unzipObjWith transformation.

[char0n]

To form a partial isomorphism with R.zipObj the transformation needs to look like this:

const patient = {
  'abbrev@1':{
    version:'1.0.9',
    resolved:'https://registry.yarnpkg.com/abbrev/-/abbrev-1.0.9.tgz#91b4792588a7738c25f35dd6f63752a2f8776135'
  },
  'shell-quote@git+https://github.com/srghma/node-shell-quote.git#without_unlicenced_jsonify':{
    version:'1.6.0',
    resolved:'git+https://github.com/srghma/node-shell-quote.git#0aa381896e0cd7409ead15fd444f225807a61e0a'
  },
  '@graphile/plugin-supporter@git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git':{
    version:'1.6.0',
    resolved:'git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git#1234commit'
  },
}

const result = unzipObjWith((value, key) => [key, { ...value, name: key }]), patient)

const expected = [
  [
    'abbrev@1', 
    'shell-quote@git+https://github.com/srghma/node-shell-quote.git#without_unlicenced_jsonify',
    '@graphile/plugin-supporter@git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git',
 ]
 [
  {
    name: 'abbrev@1',
    version:'1.0.9',
    resolved:'https://registry.yarnpkg.com/abbrev/-/abbrev-1.0.9.tgz#91b4792588a7738c25f35dd6f63752a2f8776135'
  },
  {
    name: 'shell-quote@git+https://github.com/srghma/node-shell-quote.git#without_unlicenced_jsonify',
    version:'1.6.0',
    resolved:'git+https://github.com/srghma/node-shell-quote.git#0aa381896e0cd7409ead15fd444f225807a61e0a'
  },
  {
    name:   '@graphile/plugin-supporter@git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git',
    version:'1.6.0',
    resolved:'git+https://1234user:[email protected]/git/users/1234user/postgraphile-supporter.git#1234commit'
  },
 ]
]

expect(result).toEqual(result)

So you'll need to do expected[1] to get what you need. I like that this is generic concept which plays with the rest of the zipping algos. What do you think ?

[srghma]

ok, we can add unzipObjWith too

[srghma]

found my function in nix (by chance) https://github.com/NixOS/nixpkgs/blob/70732eb4823336bb3234ea399d797c79d8dccdba/lib/attrsets.nix#L229

it's name - mapAttrsToList

[char0n]

What about calling your function objToArrayWith with alias of objectToArrayWith. The function accepts a binary transformer function and an object. IMHO having a non-homomorphic function which name starts with map doesn't make any sense. *map* should always return result of the same type as the input data.

[char0n]

Created special issue for unzipObjWith as unzipObjWith can be implemented as specialization of objToArrayWith.