In the following example, we have access to the array as numbers and arr. It seems more in line with functional programming to use the internal variable arr but what is an explicit reason why we should use it instead of the exterior variable, since, numbers and arr are both pointers to the same array value an…
Tag: functional-programming
What is the equivalent of executing multiple instance methods in functional programming in JS?
Suppose I have a class in JS with Typescript like this: When I create a Car instance and execute the execute method, two things happen: The internal state of the instance (x, y) is updated. The execute function returns a string. Now I want to write the same thing in a more FP way, making the functions pure, b…
How can I make Underscore behave like Ramda?
Two days ago, I announced a preview release of Underscore that integrates with the new Node.js way of natively supporting ES modules.1 Yesterday, somebody responded on Twitter with the following question: Can you do Ramda-style data last functions? He or she was referring to one of the main differences betwee…
Counting up and down in recursive manner in JS
I am currenty working on functional programming techniques. There are topics about this issue [ especially there is one about java ] but not about JS. I want to create a recursive function that can first, count up until the limit I decide, from the number I indicate and then start counting down when the limit…
Typescript types for a pipe() function
Consider the following TypeScript code: The pipe function simply pipes the input of one operator into the result of the next operator. Now consider this new definition of the operator type: How should the pipe function be rewritten in order for the IDE to let me know if I am using the types correctly? E.g.: c…
How can I combine multiple reducers in Ramda?
I’m trying to build reports by combining several different functions. I’ve been able to get what I want using some vanilla javascript but it’s way too wonky and I know I’d be better off if I can use a library. Ramda seems right but I’ve hit a road block and I would appreciate it …
How to return an Immutable object from a factory function in JavaScript
I have a basic function accepts Temperature data as an argument and then perform a simple temperature conversion operation on the data How can we perform the same functionality using without mutating the object? i.e, the function should not mutate the argument passed in, it should rather return a copy I have …
ramda transducers with final R.sum
I’m trying to understand Ramda’s transducers. Here’s a slightly modified example from the docs: But what if I want to sum the elements of the resulting array? The following (just adding R.sum into R.compose) doesn’t work: Answer I’d do something like this, just accumulate on top …
What is the flow of execution with this compose function passed into Javascripts reduce?
I just want to know how reduce works in the case of code below(which was provided by a stackoverflow user in my previous question, i’m asking this question as his code snippet led to me having more questions that weren’t cleared up and are too long to fit in a comment section). An array of functio…
Javascript – Using compose with reduce
I am learning functional programming with javascript. I have learned that 2 parameters are needed for reduce. Accumalator and the actual value and if we don’t supply the initial value, the first argument is used. but I can’t understand how the purchaseItem functions is working in the code below. c…