Applying one function to the result of another is known as function composition: `(f.g)(x) = f(g(x))`
Applying one function to the result of another is known as function composition: (f.g)(x) = f(g(x)).
See also pointfree.
Questions tagged [function-composition]
420 questions
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1 answer
Function composition vs decorators, in a memoized recursive Fibonacci sequence generator
I'm practicing memoization to improve recursive functions, so I wrote this memoized Fibonacci generator:
memo = {}
def memo_fibo(n):
if n not in memo:
if n < 2:
memo[n] = n
else:
memo[n] = memo_fibo(n - 2)…
Imaginary
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How do composition and currying interact?
While doing exercises of chapter 3 of the Purescript by Example book was puzzled by this:
The exercise is to write an isInBook :: String -> String -> AddressBook -> Boolean
findEntryByName :: String -> String -> AddressBook -> Maybe…
Chris Wesseling
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1 answer
Complex function composition in 1 line | Python 3.7
function composition of single argument functions is a simple 1 liner.
how would I (if it's possible) write the following composition in 1 line?
def fn(x: int) -> str:
def inner(a, b):
return strjoin(a, g(b))
return…
tex
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When nesting function calls like f(g(x)), which one is called first?
If I want to call multiple functions in JavaScript, which function will run first?
Like in this example:
sum(range(1, 10));
Does the sum function run first or does the range function run first?
I am not sure which one runs first.
user1234Es
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- 1
0
votes
1 answer
Understanding pipe function in JavaScript (functional programming)
I'm working through question 11 on bfe.dev's JavaScript coding exercises. The question asks to chain multiple basic math functions together via composition.
Here's some sample code that passes the provided test cases.
function pipe(funcs) {
let…
1sentenced
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1 answer
Composing a Java BiFunction and Consumer
Similar to this question Composing a Java Function and Consumer. What is the best way to functionally compose a java BiFunction and a Consumer? For example given some BiFunction f and some Consumer c then doing f.andThen(c)…
bootstrap2025
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Easy-to-read way of function composition in Javascript
I'm a huge fan of functional programming. I strive to use point free notation when I can. However, I often don't understand when point free notation is appropriate or when it is overkill. I typical delema that I run into is when I have a three or…
devinm
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1 answer
Function composition type inference in Dart
In dart, with generics,
the identity function works as below:
a to a:
var id = (A a) => a;
a to the list type [a]:
var list = (A a) => [a];
Now, I have function composition compose:
var compose =
(B Function(A a) f) =>
(C…
SmoothTraderKen
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2 answers
Python function composition (max recursion depth error, scope?)
What is wrong with this function? It seems like a scope error (although I thought I had fixed that by placing each callable in the list, instead of using it directly). Error is max recursion depth reached (when calling comp(inv,dbl,inc))...
Note:…
o1iver
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2 answers
Compose functions using generators
I am trying to make composition using generators.
function A(x){return 1+x}
function B(y){return 2*y}
let val=tryCompose([A,B](1); //output should be : A(B(1))
How should the generator function should look like
user8599269
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0
votes
3 answers
Nested function pointers or function composition
I am working on C implementations of calculus operations (such as derivatives, integrals, etc...). As an example, here's the template definition of my derivative function:
double derivative(double (*f)(double), double x);
Let's say I want to…
Skander J.
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Why does this composition function apply functions in the wrong order when passed as a reference?
Problem
The problem is that a composition function sometimes applies its functions in the wrong order but only when it is passed as a reference (e.g., mapValues(compose(appendB, appendA))(wordNumberMap)).
Whereas if the composition function is…
surajs02
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1 answer
A Scheme function to compose other functions
I wish to create a function that can compose two functions into one. Given g and f, it should create a function h provides the output of f as input to g. Here was my result:
(define (compose g f)
(lambda (.args)
(g (apply f (if (atom?…
Caspian Ahlberg
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haskell style generalized function composition
we have some different types
Prelude> type T1 = Int
Prelude> type T2 = Int
Prelude> type T3 = Int
Prelude> type T4 = Int
...
Prelude> type X1 = Int
Prelude> type X2 = Int
Prelude> type X3 = Int
Prelude> type X4 = Int
and some functions
Prelude> let…
Evg
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2 answers
Ramda - andThen, otherwise, andFinally?
Is there a 'finally' implementation in Ramda, for doing functional composition, and invoking a function regardless of the outcome of a promise? I want to to something like this:
compose(
finally(() => console.log("The promise resolved or…
ruckk
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