ramda.js

How to rewrite this in terms of R.compose

由 ∥☆過路亽．° 提交于 2019-12-11 02:24:31
问题 var take = R.curry(function take(count, o) { return R.pick(R.take(count, R.keys(o)), o); }); This function takes count keys from an object, in the order, in which they appear. I use it to limit a dataset which was grouped. I understand that there are placeholder arguments, like R.__ , but I can't wrap my head around this particular case. 回答1: This is possible thanks to R.converge, but I don't recommend going point-free in this case. // take :: Number -> Object -> Object var take = R.curryN(2,

Is there a name for this function

由 浪子不回头ぞ 提交于 2019-12-10 16:29:53
问题 I am looking for a name for the following function: (f, a) => () => f(a) Basically a function that returns a function which when called calls f with a . Is there a common name for this function? maybe it can be described with some Ramda magic? Edit to clarify: What I'm looking for is similar to Ramda's partial, partial(f, [a]) Except that partial is more like: (f, a) => (b) => f(a, b) I.e the b in the case of partial is unwanted. 回答1: That's a thunk. Essentially, it's a reified computation

using ramda group by property and sum results on specified property

由 寵の児 提交于 2019-12-08 21:56:10
问题 I need help transforming an array of objects using ramda; I'd like to group by a specified property sum another property on the resulting set given an array like this: var arr = [ { title: "scotty", age: 22, score: 54, hobby: "debugging" }, { title: "scotty", age: 22, score: 19, hobby: "debugging" } , { title: "gabriel", age: 40, score: 1000 } ]; if I want to group by title and sum on age it should return the following summary of values var arr = [ { title: "scotty", age: 44, hobby:

Node Ramda + find the object based on value

由 大憨熊 提交于 2019-12-08 11:56:20
问题 Possible to get object based on the value? In below sample json, the key name have type , so based on type value need to fetch the results. For example if type='user' then fetch the result only for users object not for employee object. Here I am struggling have both keys(users and employee), Could you please suggest to how to approach var list =[ {"doc":{"type":"user","Title":"test1","Relations":{"users":[{"name": "user1"},{"name": "user2"},{"name": "user3"}],"employee":[{"emp": "user2"}]}}},

Change Value Properties in Object with Ramda Lenses

由 回眸只為那壹抹淺笑 提交于 2019-12-07 15:02:40
问题 I would like to know how can I change object properties with Ramda Lenses. Currently, I have a deep state : buckets[ blocks[ messages[ replies [ {id: 0, text: 'text 0', value: 'simple value 0'}, {id: 1, text: 'text 1', value: 'simple value 1'}, {id: 2, text: 'text 2', value: 'simple value 2'}, ... ] ] ] ] I have a basic payload. I would like to get the property and the value, and set the old value by the new value in my state, for example with this payload : {text: 'new_text'} or {value: 'new

How to perform a nested update using Ramda in the given object structure?

由 允我心安 提交于 2019-12-06 11:39:01
Assuming the follow object how is it possible to use Ramda to perform a nested update in a criteria given an application, criteria ID and data? const application = { id: 'a1', features: [ { id: 'f1', criterias: [ { id: 'c1' } ] }, { id: 'f2', criterias: [ { id: 'c2' }, { id: 'c3' } ] } ] } The function would look something like this: const updateCriteria = (application, criteriaId, data) => // magic... updateCriteria(application, 'c2', { name: 'foo' }) // output: { // id: 'a1', // features: [ // { // id: 'f1', // criterias: [ // { id: 'c1' } // ] // }, // { // id: 'f2', // criterias: [ // { id

How to fork and merge monads?

由 六眼飞鱼酱① 提交于 2019-12-06 05:28:06
I am learning monads and doing my first "login" case. The steps are simple: User input userName and password; From database, get user by userName, and get its password saved in database; compare the input password with the one in the database. From the above, there is a requirements to fork 2 monads and merge them to compare. I read nearly all javascripts FP books and monads implementations I can think of, but still cannot found any solutions. The below is what I got so far, it works, but it looks complex and not very well readable. I am wondering if there is a standard way to handle this

difference between chain() and map() in ramda.js

由 て烟熏妆下的殇ゞ 提交于 2019-12-05 21:05:33
What is the difference between chain() (from ramda package) and map() in Javascript? In both functions the programmer inputs an object and some lambda/function and gets a certain calculation of it. Thanks. Abstract Types chain and map each operate on an abstract type. map operates on any Functor . This is any item with a map function that obeys certain laws. chain operates on a Chain element. Similarly, this is something with a lawful chain function, as well as having lawful apply and map functions. Ramda provides map and chain functions that will work with types fulfilling these contracts. It

How to use Ramda to find matching object in Array by key value

由 浪尽此生 提交于 2019-12-05 09:45:18
Ramda REPL example var portfolio = [{ticker: "aa"}, {ticker: "bb"}]; var ticker = {ticker:"aa"}; var exist = R.find(R.propEq('ticker', ticker), portfolio) console.log(exist) Currently this is giving me undefined , however R.propEq should find the matching object by key ticker in port I thought? As you say, you can solve it by passing in the key to propEq : R.find(R.propEq('ticker', 'aa'), port) Another option is to use the eqProps function, which tests if two objects match for the named key: R.find(R.eqProps('ticker', ticker), port) You can see the first or second version in the Ramda REPL. Ah

When is it appropriate to choose point-free style vs a data-centric style in functional programming?

由 最后都变了- 提交于 2019-12-04 04:43:20
问题 In case it matters this is about functional programming in JavaScript and in my examples I’ll be using Ramda. While everybody at work has fully embraced functional programming, there’s also a lot of discussions around how to do it “right”. These two functions will do exactly the same thing: take a list and return a new list in which all strings have been trimmed. // data-centric style const trimList = list => R.map(R.trim, list); // point-free style const trimList = R.map(R.trim); So far so
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