Functional programming is a paradigm which attempts to solve computational problems by the chained evaluation of functions whose output is determined by their inputs rather than the programme state. In this style of programming, side effects and mutable data are deprecated and usually strictly ...

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58
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9answers
4k views

Should we define types for everything?

Recently I got into a problem with the readability of my code. I had a function that did an operation and returned a string representing the ID of this operation for future reference (a bit like ...
-2
votes
0answers
34 views

Concepts related to higher order functions [on hold]

I am trying to understand higher order functions. I know that they are functions that can take functions as parameters and return functions as results. But I feel there is more to it, for example, I ...
-1
votes
1answer
138 views

Should we ignore object-oriented and study functional? [on hold]

I am programming in Haskell. I was wondering since that Functional programming is so perfect, like codes are more concise lesser complexity makes us think more about how program should work ...
0
votes
1answer
72 views

Haskell types for functions

I don't understand the answer to this question: Q: Can Haskell find a type for the function selfapply defined by: selfapply f = f f A: The function selfapply is not typeable in the simple system of ...
-4
votes
0answers
76 views

Does imperative programming have a (mainstream) future? [on hold]

I have written a few small programs in Python and C++ and am currently learning F# (I am already quite familiar with FP concepts, as a result of reading the Learn you some Haskell tutorial until the ...
1
vote
1answer
194 views

What is the “->” symbol called?

I have seen the -> operator/symbol in Java 8 predicates recently and wondered what its name is. I know that it is used in lambda expressions, but I know that the symbol for lambda is λ, so that's ...
2
votes
2answers
97 views

Dealing with states in a immutable approach [on hold]

I want to know how to deal when you have some states in a program, with functions that depends on them, but with a immutable approach. I read some examples and questions, but all focus in a small ...
0
votes
3answers
106 views

Why python function programming functions are not collection methods? [duplicate]

In other words, is there a Python design related reason for it to be so? Functions like map, filter, reduce etc. are just plain functions. Is it just a poor design choice (if it is a good one, ...
7
votes
0answers
194 views

Maintaining State without assignment

I am learning functional programming and I have trouble understanding how some particular scenarios are implemented without the use of assignment. The following simple problem pretty much sums up my ...
0
votes
1answer
139 views

Advantages of the imperative style over the functional style [duplicate]

There's a lot of hype over functional languages right now, and I've spent the last year studying Haskell as my intro to FP as a result. Seeing the advantages FP provides is easy (such as referential ...
4
votes
1answer
136 views

Pattern matching against two similar types

What is the best way to handle pattern matching in the following situation? sealed trait Metadata final case class Metadata1() extends Metadata final case class Metadata2() extends Metadata final ...
0
votes
0answers
30 views

Accessing intermittently available resources with transactions and post-access cleanup in a generalized, functional, composable way

The following psuedo-code illustrates what I'd like to be able to do. Is there a way to accomplish something like this in Scala?: trait IntermittentlyAvailableResource trait ...
0
votes
1answer
66 views

FP: Capturing the characteristics of a process which blocks, causes side-effects, and may fail

I have a driver function modifyFile that interacts with many sources in the outside world (e.g. HTTP, filesystem). Let's say the code is as such: def downloadFile(from: String, to: String): Try[Unit] ...
11
votes
2answers
303 views

Is higher-rank parametric polymorphism useful?

I'm pretty sure everyone is familiar with generic methods of the form: T DoSomething<T>(T item) This function is also called parametrically polymorphic (PP), specifically rank-1 PP. Let's ...
11
votes
3answers
3k views

What is the name of a function that takes no argument and returns nothing? [closed]

In Java 8's java.util.function package, we have: Function: Takes one argument, produces one result. Consumer: Takes one argument, produces nothing. Supplier: Takes no argument, produces one result. ...
6
votes
0answers
143 views

Is it common practice to transform requirement specifications into predicate logic for functional programming?

I've recently been assigned to work on a small project which is being implemented in Haskell. Coming from an OO/imperative background, I'm used to converting requirements/user-stories into use-cases ...
0
votes
0answers
96 views

What is the relationship between “flux” and pure functional reactive programming?

Flux, as far as I understood, is a technique about dealing with the dataflow of an application unidirectionally, keeping state isolated from the rest of the program in read-only, self-contained ...
5
votes
3answers
445 views

Is Functional Programming a viable alternative to dependency injection patterns?

I have recently been reading a book entitled Functional Programming in C# and it occurs to me that the immutable and stateless nature of functional programming accomplishes similar outcomes to ...
2
votes
1answer
77 views

FP and board game state

I wanted to implement the game of Tic Tac Toe using a functional language (in my case, Scala) but I'm unsure how to go about managing the board game state after each player makes their move. I ...
1
vote
1answer
115 views

Functional Programming style: How to write functions - explicit currying, implicit currying or lamdas?

So I have been using F# for a while and studying a bit of Haskell on the side and I have realized I could rewrite the exact same function one of three different ways. Either with implicit currying, ...
-1
votes
2answers
202 views

Is functional language without runtime written in C possible?

Every functional language that compiles to native code relies on quite big runtime written in C programming language (well at least ones that I know of, for example Haskell, OCaml, Gambit/Chicken ...
-1
votes
1answer
67 views

Significance of '__name__ ' attribute in python

1) Below python code, >>> def f(): return creates a function type object which has __name__ attribute with value 'f' which looks fine. But, 2) Below line of code, >>> x = ...
5
votes
3answers
790 views

Can “higher order function” feature allow/maintain abstraction and encapsulation?

Below is the function repeat written using a functional paradigm, such that when called as repeat(square, 2)(5) it will apply the square function 2 times on the number 5, something like ...
1
vote
0answers
89 views

How and where to make global function file in jsp sevlet web application

I am making a website in Servlet&JSP. I am looking for good way to make a specific function file from where I can call and declare my common functions. If I made a java file function. Java, so is ...
-4
votes
4answers
129 views

Does this python program obey functional paradigm?

Below is the hailstone sequence program considering the rule of thumb in functional programming. The simple rule of thumb is: if you can replace any expression, sub-expression or subroutine call ...
4
votes
1answer
106 views

How would I isolate changes to mutable state if I need to run two queries to get the final result?

I'm working on some code that takes search criteria from a Rest API and uses it to query a remote API to return results. As an exercise, I wanted to try to separate all state changes to one place, as ...
1
vote
1answer
117 views

How do I enforce 'referential transparency' in this program?

Below is the python program written to follow the rule of thumb in functional programming. The simple rule of thumb is: if you can replace any expression, sub-expression or subroutine call with ...
0
votes
1answer
100 views

Abstracted better? Data driven string creation

I am trying to post this question neutral of programming language so it helps the widest audience. But for those who must know, I am using Objective-C and iOS frameworks. The background: I have a ...
0
votes
1answer
55 views

Dealing with error in data - Idempotent approach

A prior question had an answer that interested me from a design perspective. I work in geospatial data and occasionally have to deal with voids when I read these binary files into my product. What is ...
16
votes
6answers
1k views

Does functional programming increase the 'representational gap' between problems and solutions? [closed]

Since machine language (e.g., 0110101000110101) computer languages have generally evolved to higher forms of abstraction, generally making it easier to understand the code when it's applied to a ...
0
votes
1answer
52 views

Choose approaches for updating an object

Say I have a simple object created by from user input: var input = { url: 'http://example.com/', path: 'abc', user: 'adam' }; And I am to write function(s) that update url and path properties ...
2
votes
1answer
97 views

How to make an interpreter for a stack of Free Monad Transformers

I like the idea of using Free monads to "purify" code and I've used it in some simple scenarios. However, I can't seem to figure out how to write an interpreter for a Free monad transformer. In ...
6
votes
1answer
162 views

Is the use of DSLs in a state monad a good approach to building complex stateful computations?

First, sorry if that title makes no sense. I am a little out of my depth here with the terminology. So, imagine that I'm writing a text editor in Haskell. For the purposes of this question, let's ...
0
votes
1answer
175 views

What kind of reputation does Java 8 have among “enterprise” companies? [closed]

Are the new, functionally-inspired features of Java 8 well-regarded within the enterprise development community? Have they been adopted by large companies? Have coding standards been updated to ...
14
votes
9answers
2k views

What would be good factual arguments to convince high level management to consider functional programming? [closed]

There are tons of "theoretical" arguments for why functional programming is a Good idea (too many for that to have stayed as an open question, and correctly so). However, most of them are arguments ...
2
votes
3answers
206 views

Declaring lambdas in Java8

What would be the best practice to declare lambdas in Java8 code? How it was designed to be used? For example, let's say that we have a method that accept a Function. I want to provide function ...
18
votes
1answer
1k views

Confusion between F# and C# [duplicate]

I am fairly new to functional programming and C#/F#. What is unclear to me is: Can you do functional programming in C# and/or in F#? Or is it something like, you write some OO code in C#, and some FP ...
2
votes
2answers
330 views

Should we refactor our existing codebase to use functional programming, especially streams? [closed]

We have a large project written in PHP. It almost exclusively uses imperative operations, as in example 1. Should we refactor our existing code to use functional operations? Do you think that the code ...
4
votes
1answer
204 views

Functional programming for loop side effect

I am trying to get my head around as to why having a local variable or a for loop inside a function is not considered to be pure functional programming. Given this function: int as_int(char *str) { ...
1
vote
4answers
410 views

Is it possible to use functional paradigm in imperative languages?

If I understand the concept correctly the goal, which functional languages are trying to achieve is to eliminate any side effects from functions and to eliminate a state. The rationale behind this is ...
-1
votes
1answer
82 views

New DDD, context-oriented, functional… approach in building business layer [closed]

We are building some business modules that must be intuitive for developers to use, so the code itself explains and forces developers to use it in certain way. This applies both for enhancing the ...
13
votes
1answer
471 views

What is Banana split and fusion in functional programming?

These terms got mentioned in my university course. Quick googling pointed me to some university papers, but I am looking for a simple explanation.
2
votes
1answer
286 views

In what way are union types better for correctness than a common interface?

I've just recently started familiarising myself with functional programming, mostly via F#, and there's one particular functional idiom that I'm not fully understanding the benefits of. I've seen it ...
0
votes
1answer
166 views

Programming CPU Emulator Functional Style [closed]

I want to write an 8086 CPU emulator in javascript, functional style. How would one conceptualise / design an 8086 emulator, or any CPU emulator that has registers and realmode memory access in a ...
10
votes
5answers
597 views

Why do functional programs have a correlation between compilation success and correctness?

I've been trending toward functional programming for 4 years now, ever since I first started working with LINQ. Recently, I wrote some pure functional C# code and I noticed, first hand, what I've ...
2
votes
3answers
203 views

What do I use for a variant in a UML class diagram?

Does standard UML specify how a variant (aka tagged union, discriminated union, sum type, etc) should be depicted in a class diagram?
2
votes
1answer
275 views

Is the application architecture of Facebook Flux a new idea?

Facebook announced that it's using the architecture they call Flux to develop their projects. It consists of a single direction dataflow, and concepts like a Dispatcher, Stores and Actions (well ...
0
votes
3answers
235 views

Reference counting & GC in LISP [closed]

What is the main method for reclaiming the memory in LISP? Does LISP really need garbage collection? Would not reference counts suffice? I just wanted to know whether reference counts are enough ...
0
votes
1answer
140 views

How to Understand the concept of Immutablity in Functional Programming [duplicate]

I have come across several sources that say that immutability is a concept that is followed in functional programming. I have come across this concept when looking at collections in Scala where a new ...
3
votes
0answers
176 views

Lightweight data modeling vs traditional classes [closed]

I've heard a lot of talk about using lightweight data modeling as of late. Especially in relation to the Clojure programming language. What is it and how it differs from traditional classes regarding ...