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
0
votes
1 answer
Take a list of functions and compose the list with a value
I'm currently attempting to do this problem from the ebook, Haskell School of Music:
Define a function applyAll that, given a list of functions
[ f1, f2, ..., fn ] and a value v, returns the result f1 (f2 (...(fn v)...)).
For example:
applyAll…
Meta
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0
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1 answer
Action Compositon Play2 Java
I'm currently developing a web service with Play2 and I have a problem with action composition.
Here is one of the methods available for my web service :
@Authenticated(Secured.class)
@BodyParser.Of(BodyParser.Json.class)
public static Result…
c4k
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1 answer
Should I return the object itself just for function chain
I have been wondering whether should I return the object itself from a setter or procedure (returning void originally), so that all the function can chain together.
We've all been taught to return void when there is nothing to return, but is…
user15459834
-1
votes
1 answer
TypeError: Object is not a function or its return value is not iterable, when i use useState (function component)
const [text, setText] = useSate('')
const [day, setDay] = useSate('')
const [remainder, setRemainder] = useSate(false)
Sava
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1 answer
Refactor `f(g(x))(x)` so that I can compose this nicely
I have a couple of functions that currently are written (in abstract form) like this...
const someFunction = x => f(g(x))(x);
i.e.
pass x into g to get the output.
Then pass that output into f to get a function.
And then pass x into that…
Fogmeister
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-1
votes
2 answers
Confusing function application and function composition in Haskell
The operation
(filter (`notElem` "'\"").[(1,'a','%',"yes")])
gives an error. How can apply this filter on that list properly?
thetux4
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1 answer
"foo" is "a -> b -> c". "foo . foo" is also "a -> b -> c". Does Haskell treat them exactly the same in terms of speed?
foo :: a -> b -> c
foo = undefined
ghci> :t foo
foo :: a -> b -> c
ghci> :t foo . foo
foo . foo :: a -> b -> c
ghci> :t foo . foo . foo
foo . foo . foo :: a -> b -> c
And so on.
The types are the same. We also clearly see, just by looking at the…
haskellHQ
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-1
votes
2 answers
Composition of "pow" functions in C
I am trying to integrate a couple of equations, but the program fails to compile. The error message that appears says: "too many arguments to function pow"
I will show the problematic part of the code and then make two specific questions.
#include…
Gato Mazzei
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3 answers
Function composition with just lambdas in python
Is there a way to do the following in just one line with lambdas in python?
squared = lambda x : x**2
cubed = lambda x : x**3
squareCubed = lambda x : squared(cubed(x))
without using any helper functions or reduce.
print(squareCubed(2)) # > 64
cvb0rg
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votes
1 answer
why is juxt named after juxtaposition?
Why is Clojure's juxt named after juxtaposition? I don't see what is being juxtaposed. This is in contrast to partial and comp which have intuitive naming.
m33lky
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-2
votes
2 answers
Can this expression be written without brackets or back-ticks?
mul (add 2 3) 5
Can the dot (.) and dollar ($) operators alone replace the brackets?
The mul and add functions are filler, i.e. the order of application must stay the same.
This is an exercise to better understand the aforementioned operators.
Ware
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-2
votes
2 answers
Javascript: Compose a function with argument placement instructions for each composition
I'm looking for a javascript function that can:
Condition (I)
compose another function when it does not have recursion in its definition, kind of like in maths when the function is given a power, but with multiple arguments possible in the first…
Sophiα2329
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-2
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3 answers
Composite Functions in C
If i have a composition of functions f(f(f(f(x)))) how can i write it as function in C ? Is it possible to write it with recursive algorithm?
For example what happens if we have the following function:
f(x)=cosa*X1+cosb*X2 where x=(X1,X2)
Otinane
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votes
1 answer
haskell Chess Knight Tour: Function composition
I've a hard time understanding a Chess Knight problem concerning
function composition. The exercise is a generator/filter/selector
chain with a given wrapper function (knightProblem) which glues everything together.
It is unclear to me how the…
SnDnFn
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votes
1 answer
Composing applicative functions
Please implement the function:
composeApplicative :: (Applicative f) => f (b -> c) -> f (a -> b) -> f (a -> c)
Such that:
(composeApplicative f g) <*> x == f <*> (g <*> x)
Or alternatively, explain why this can not be done?
Clinton
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