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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6
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3answers
852 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
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0answers
161 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
1answer
122 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
140 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
104 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
102 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 ...
17
votes
6answers
2k 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
63 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
246 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
194 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
336 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 ...
3
votes
3answers
468 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
371 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
964 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
779 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
107 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 ...
16
votes
2answers
1k 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.
4
votes
2answers
699 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
316 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 ...
12
votes
5answers
766 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 ...
4
votes
3answers
489 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?
5
votes
2answers
706 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
510 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 ...
3
votes
0answers
226 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 ...
1
vote
1answer
354 views

What was the influence of Chris Okasaki's data structures on Scala? [closed]

I heard a friend say: The first real use of Chris Okasaki's book was in Clojure's data structures I heard another friend say: No, they influenced the design of Scala in quite a subtle way. ...
3
votes
6answers
2k views

How can IO cause side effects in Functional Programming? [duplicate]

Whenever I read about Haskell, I find that IO can cause side effects. But I do not understand how it would do it? Do we mean that we are writing to a file from one lazy sequence and another lazy ...
12
votes
5answers
2k views

Why is reading from memory not a side-effect but reading from a file is?

What does exactly make reading from the process memory a pure operation? Suppose I created an array of 100 integers in the global memory and then took the 42th element of this array. It is not a side ...
3
votes
3answers
1k views

Help me to understand 'stateless' software in functional programming

I'm an experienced software engineer, and have experience in a range of languages from PHP, Ruby, C#, Java - the last few years I've primarily worked in Java. I'm now learning Scala, and it's my ...
5
votes
2answers
817 views

Alternative to language purity

Purity One of the interesting concepts in Haskell is the purity. However, I am wondering what the pragmatic reasons behind this is - let me explain a bit more before you reject my question. My main ...
2
votes
0answers
97 views

What makes the functional and logic programming paradigms well suited for programming AI? [duplicate]

I have been researching different programming paradigms. I have found a lot of people saying that one of the areas where logic and functional programming are particularly good is programming AI, but I ...
3
votes
1answer
712 views

How to avoid global state without large function signatures?

So, there are some good answers to this question, namely: Why is Global State so Evil? I have a specific question about the alternatives Mikera proposed as the answer with the second most up-votes. ...
0
votes
2answers
200 views

Is this instance of mixing FP and OOP a good design?

I had a strange-feeling pattern come up in some code I was writing. In a project with user accounts, there was a lot of code that needed to do common things such as creating accounts, deleting them, ...
3
votes
1answer
172 views

How do I avoid duplicating utility functions across modules?

I've seen this question but it doesn't help me because I'm writing functional code (Standard ML) and the answers there are heavily focused towards OOP (the OP is advised to use the Facade pattern, to ...
8
votes
2answers
1k views

Applying the principles of Clean Code to functional languages

I'm currently reading Robert Martin's Clean Code. I think it's great, and when writing OO code I'm taking his lessons to heart. In particular, I think his advice to use small functions with meaningful ...
25
votes
3answers
4k views

What is referential transparency?

I have seen that in imperative paradigms f(x)+f(x) might not be the same as: 2*f(x) But in a functional paradigm it should be the same. I have tried to implement both cases in Python and Scheme, ...
2
votes
1answer
122 views

Expected time for lazy evaluation with nested functions?

A colleague and I are doing a free R course, although I believe this is a more general lazy evaluation issue, and have found a scenario that we have discussed briefly and I'd like to find out the ...
2
votes
1answer
146 views

What is the value of a let expression

From what I understand, every code in f# is an expression, including let binding. Say we got the following code: let a = 5 printfn "%d" a I've read that this would be seen by the compiler as let a ...
5
votes
2answers
237 views

How can I make sense of the word “Functor” from a semantic standpoint? [closed]

When facing new programming jargon words, I first try to reason about them from an semantic and etymological standpoint when possible (that is, when they aren't obscure acronyms). For instance, you ...
3
votes
1answer
545 views

Is Lambda Still Supported In Python?

Only one or two years ago, I remember reading Python constructs that would be removed from Python -- reduce was one of them -- and other constructs that would be emphasized like comprehensions and ...
4
votes
1answer
195 views

How should I recursively process a file in Haskell?

Basically I'm expanding a literate program in Haskell. There are two things I need to look for to expand. Here's an example file: program.c.lit: ============== Some comments in the source file that I ...
2
votes
1answer
401 views

Difference between Yesod and Ocsigen web frameworks [closed]

I have been looking at web-frameworks in functional languages and eventually found Yesod and Ocsigen interesting. As far as I understand, they leverage the type system to statically prevent basic ...
6
votes
1answer
342 views

How to represent hard-to-calculate “properties” of “objects” in functional code?

I have a polyline "class" in my Clojure program, which is represented by a vector of points. (It's not really a class or anything.) The polyline's length (in the geometric sense) is something that is ...
1
vote
1answer
722 views

When does a Monad become a hammer?

I realize my precursory understanding on Monads is severely lacking in detail considering my knowledge comes mostly from Douglas Crockford's Monads and Gonads talk and complicated with my sevear ...
5
votes
4answers
779 views

Why not apply Interface Segregation Principle to “extreme”

Providing that clients would typically consume just one method, though methods would be conceptually related, why not always apply the Interface Segregation Principle to the extreme and have [many] ...
30
votes
5answers
3k views

Why do some functional programming languages use a space for function application?

Having looked at some languages for functional programming, I always wondered why some fp-languages use one or more whitespace characters for function application (and definition), whereas most (all?) ...
4
votes
2answers
772 views

extensible effects in purescript

In Purescript, IO an other effects are managed with the Eff monad, and extensible effects, which are declared like this: main :: Eff (trace :: Trace, random :: Random) {} So if I understand well, ...
5
votes
3answers
744 views

Functional programming strategies in imperative languages

I've been convinced for awhile now that some strategies in functional programming are better suited to a number of computations (i.e immutability of data structures). However, due to the popularity of ...
13
votes
8answers
2k views

Mental Models or Real-World-Metaphors for Functional Programming

Does anyone have a good mental model or metaphor for functional programming which references something in the real world? Object Oriented programing intuitively makes sense to me. There are things ...