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 ...
2
votes
2answers
99 views
Simulated functional programming in C — passing the entire program state as a function argument
I have a struct called State which holds all the variables for the program. Rather than being modified by functions directly, it is the value returned.
Here is some code:
#define USERNAME_LENGTH 20
#...
4
votes
1answer
80 views
Why the name MailboxProcessor in F#?
It seems that the standard practice is to immediately alias MailboxProcessor<'T> to Agent<'T>. So why the name in the first place anyways? Why don't they just call it Agent<'T>, if ...
2
votes
1answer
51 views
Pure functions and the outer scope [duplicate]
Excuse my ignorance, I come from the C family of languages but zero exposure to functional languages. I've read that pure functions only generate output based on a given input. Same input gives the ...
8
votes
4answers
498 views
Do non-OOP paradigms support concepts such as encapsulation?
One of the important concepts in Object Oriented Programming is Encapsulation. However, lately the software world seems to be tilting in favour of other paradigms like functional programming.
It ...
0
votes
0answers
41 views
Functional reactive ideomatic 'OR' function
I'm would like to know your opinion of what is an ideomatic way writing a OR function in functional reactive programming.
That is, if I have x number of signals which can return a truthy or falsy ...
-1
votes
0answers
42 views
Functional JavaScript, remove assignment [migrated]
How can I avoid the self variable here?
function urlBuilder(endpoint){
var status = ["user_timeline", "home_timeline", "retweets_of_me", "show", "retweets",
"update", "...
2
votes
2answers
91 views
Unknown number of arguments in currying
Hypothetical situation - can a currying function have an unknown number of arguments (kind of like varargs)
Eg in Python:
addByCurrying(1)(2)(3)(4)
Should equal 10
addByCurrying(5)(6)
Should ...
1
vote
1answer
99 views
What are the factors that prevent wider adoption of languages with dependent types?
While there are/were several languages with dependent types, like Agda, Coq or Epigram, none seemed to gain wider adoption. Despite that dependent types allow very strong type safety, up to writing ...
1
vote
2answers
63 views
Concerns on lazy evaluation and infinite data structures
I am trying to learn how lazy evaluation works because I'm going to implement try to implement it in the programming language I'm developing (I know it isn't the best thing to do (to try to implement ...
0
votes
0answers
31 views
Reducing a list into a Map of ranges
I have nested structures that record ranges. The sub-structure record sub-ranges.
For example:
[
{
type: "A",
start: 0,
end: 2,
...otherInfo,
sub: [
{
type: "B",
...
2
votes
2answers
109 views
Designing the recursive solution
I understand the recursion and find it useful and intuitive while solving problems on trees but for many other problems recursion never fails me to leave puzzled. Recently I was solving the following ...
0
votes
1answer
60 views
What is the difference between Applicative and Generative Modules, and Type Classes?
Reading the comments to this blog post made me realize I don't know much about some really interesting functional mechanisms between languages like Haskell, OCaml and Standard ML. I'd love a high-...
3
votes
1answer
119 views
What is the functional programming method for combining two “streams” of data?
I'm trying to figure out what the appropriate way to deal with this problem is in a functional way. I'm assuming there's a functional data structure or technique that will make this easy to handle.
...
1
vote
2answers
178 views
Simulating objects in Functional Programming
In FP vs. OO, from the trenches, Michael Fogus says:
Whenever I write some code to deal with data about people then functional programming seems to work best.
Whenever I write some code to ...
2
votes
1answer
61 views
Preserving log of immutable Data Structure changes
I have large and complex immutable data structure (language is F#, but should be applicable to any language really) where I defined a lot of functions making changes and returning new instances of ds ...
2
votes
2answers
130 views
Nested functions: should I explicitly pass arguments or rely on scope?
Suppose I have a function f that uses two helper functions h and g to get the job done. There are two possible ways of dealing with this situation.
(1) take explicit arguments and returns new objects ...
1
vote
0answers
41 views
Algorithm to generate all paths between two vertices of a graph in F#
Following a functional programming approach (no mutable data structures, recursion, etc) I have written a script in F# to generate all paths between two vertices of an undirected, unweighted graph. I ...
6
votes
1answer
131 views
How do you model has-a (aggregation) relationships in functional programming languages
Just to be on the same terms:
Aggregation is a has-a relationship, where the owned components can exist independently of the owning component.E.g. a pond and some ducks swimming in it. A duck leaving ...
1
vote
1answer
68 views
What is the connection between type inference and advanced type systems?
I don't understand the connection between type inference and advanced type systems. I don't see why Haskell or Standard ML or OCaml could not have existed without type inference. My only guess is that ...
1
vote
1answer
96 views
How do you organize your hoisted functions?
In a module (file) I organize several functions related to a specific domain task. I usually put the function linearly from top to bottom, then compose a functional call on the bottom. Doing so I can ...
4
votes
3answers
147 views
How are typeclasses in functional languages different from interfaces in OO languages?
I'm learning about paradigms of functional languages. So I've read that while Subtype polymorphism is typical for OO languages, Parametric polymorphism is typical for functional languages.
But I ...
5
votes
4answers
670 views
Minimal programmer's definition of a monad
I am trying to formulate a definition of a monad without needing mathematical terms or Haskell to understand.
Can a monad be thought of as a function that accepts a value and wraps it such that it ...
2
votes
2answers
122 views
What is the most idiomatic way to iterate collection with different action for first element?
Sometimes we meet a situation where we should iterate (or map) over a collection, applying the same procedure (function) for all elements except the first one. The simplest example is finding the max ...
2
votes
0answers
63 views
Elements of structure in a functional program
In object oriented, we have requirements, use cases, and UML which can form a nice conceptual framework. The goal there, is to define objects, their responsibilities, behaviors and communications ...
1
vote
1answer
131 views
Functional Programming in PHP
Modern PHP is mostly written Object Oriented. Other than the fact that there is inertia towards the Object Oriented in the PHP community, is there anything about the language itself that would make it ...
0
votes
2answers
142 views
How do you deal with a mutable buffer in a functional space?
I have a stream parsing method in C# that reads portions of a protocol frame from the STOMP protocol; the specification isn't the important part for the question though. What is important is that I ...
5
votes
1answer
281 views
How to move from OOP object composition to FP function composition in C#
I have been working for a few weeks on a new web project and I am realizing that all I am doing is basically calculations and transformations on data, and that most of my classes do not contain any ...
16
votes
6answers
4k views
A language based on limiting amount of arguments passed to functions
The idea is inspired by the fact operators such as +, -,%, etc. can be seen as functions with either one or two arguments passed, and no side-effects. Assuming I, or someone else, writes a language ...
3
votes
1answer
173 views
Are promises functional
Functional programming is often explained to agree with lazy evaluation.
As far as I know lazy evaluation means that a method gets called if the evaluator/browser/etc. thinks that is the next best ...
7
votes
2answers
309 views
What is a Comonad and how are they useful?
Recently I've been dusting off my knowledge on how Monads work. I've also been introduced to the concept of a 'Comonad', which is described as the inverse of a monad. However, I am impossible to wrap ...
7
votes
2answers
196 views
Data structure for two-dimensional board games in Functional languages
I am creating a simple MiniMax implementation in the functional programming language Elixir. Because there are many perfect-knowledge games (tic tac toe, connect-four, checkers, chess, etc), this ...
0
votes
2answers
137 views
Advantages of workflow based software development vs normal programming based software development
I am very new to workflows, and trying to understand why workflows are used. While surfing internet, I haven't found any strong point for using workflows.
Please explain me the scenarios where ...
2
votes
1answer
98 views
Programatically determine that some functions are pure
I saw this question that shows it is impossible to programatically determine if a javascript function is pure, but is it sometimes possible to affirm that a function is pure - so something like...
...
7
votes
0answers
302 views
What lambda function optimizations, if any, are planned for Java 9 and beyond?
I'm working on a high-performance project where Java 8's lambda functions are enormously useful. I've found, however, that they're memory inefficient when used en masse. For example, suppose I need to ...
5
votes
0answers
162 views
Does it make sense to apply the principles in Redux to OO languages?
Redux is essentially functional programming, and it makes a lot of sense. As I move back to a non-javascript OOP language in a different project I would like to apply the same principles such as ...
6
votes
0answers
109 views
How does the Free monad and Reactive Extensions correlate?
I come from a C# background, where LINQ evolved into Rx.NET, but always had some interest in FP. After some introduction to monads and some side-projects in F#, I was ready to try and step to the next ...
1
vote
2answers
54 views
Type of map for Try[T]
I was looking at the type of map for Try[T] in Scala, which is:
def map[S](f: T=>S): Try[S]
From Haskell, I am used to the type of map being:
map :: (a->b)->[a]->[b]
This seems very ...
3
votes
2answers
139 views
Referential Transparency by using Zero References?
Referential Transparency is one of the corner stones of functional programming that allows us to apply equative reasoning to our code. However it does so at a cost to performance, by use of immutable ...
0
votes
2answers
153 views
Almost point-free style
Programmers often talk about point-free style. In contrast to the imperative style (pseudocode):
h := function(x) {
y := f(x)
z := g(y)
return z;
}
one might write the following point-free:
...
2
votes
1answer
84 views
Term for the opposite of the functional Compose operator
In functional programming, given a function f and a function g we can define a function . (compose):
let (.) f g = fun x -> g (f x)
Is there a term for the function which applies arguments in the ...
4
votes
2answers
93 views
Under what scenarios would 'functional' `Try` objects be more or less beneficial than 'rx' `Try` objects?
Definitions used by this question:
'functional' Try is what https://github.com/lambdista/try is. Success and Failure are subclasses of Try. Exceptions aren't thrown by the called function.
'rx' Try ...
14
votes
5answers
476 views
Is it still valid to speak about anemic model in the context of functional programming?
Most of DDD tactical design patterns belong to object-oriented paradigm, and anemic model describes the situation when all business logic is put into services rather than objects thus making them a ...
35
votes
7answers
4k views
What do you call a function that's pure, meaning the same input will always return the same output, but also has side effects?
Say we have a normal pure function such as
function add(a, b) {
return a + b
}
And then we alter it such that it has a side effect
function add(a, b) {
writeToDatabase(Math.random())
return ...
2
votes
6answers
269 views
How does immutability remove the need for locks when two threads are trying to update the shared state?
Okay so I read through this:
Does immutability entirely eliminate the need for locks in multi-processor programming?
And this was the main takeaway for me:
Now, what does it get you? ...
2
votes
4answers
556 views
What is Big-O notation for purely functional languages?
Is it still relevant?
Instead of
var result = new List<int>();
for (var i = 0; i < prev.Count; ++i)
{
result.Add(prev[i] * 2);
}
where the result.Add, prev[i], and * 2 instructions ...
5
votes
2answers
142 views
Using queues to decouple functions/avoid direct calling?
Kind of a functional programming newbie question here:
I've been reading the transcripts of some of Rich Hickey's talks, and in several of his more well-known ones, he recommends using queues as an ...
5
votes
2answers
130 views
What is the difference between explicit parameters and closures
In F#, a tail recursive List.filter function can be implemented like:
let filter f =
let rec filterImpl f acc = function
| [] -> List.rev acc
| h :: t -> filterImpl f (if ...
1
vote
3answers
164 views
Logic Programming(Unification) vs List Comprehensions (in Functional Programming)
I found this answer on StackOverflow very clear to explain the difference beween the Logic Programming paradigm and the Functional Programming paradigm:
The thing that makes logical append ...
5
votes
3answers
246 views
Should databases be viewed as Monads?
Because any kind of persistence updates/inserts/deletes represents in some sense a kind of state change in a database, it makes me wonder whether databases can be considered monads. We say the same ...
3
votes
3answers
109 views
Declarative programming for deterministic real time control
Let's say you want control a motor in real time. Normally you would use a microcontroller or PC with e.g. c-programming language. So you would use an imperative approach. You tell the microcontroller ...
