Multivariate function composition
Let's consider the following:
f: Int -> Int -> Int -> Int
f a b c = a + b + c
g: Int -> Int
g x = x * 2
now, I'd like to create a composed function like
f(g(a), g(b), g(c))
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
elm
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
add a comment |
Let's consider the following:
f: Int -> Int -> Int -> Int
f a b c = a + b + c
g: Int -> Int
g x = x * 2
now, I'd like to create a composed function like
f(g(a), g(b), g(c))
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
elm
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
add a comment |
Let's consider the following:
f: Int -> Int -> Int -> Int
f a b c = a + b + c
g: Int -> Int
g x = x * 2
now, I'd like to create a composed function like
f(g(a), g(b), g(c))
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
elm
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
Let's consider the following:
f: Int -> Int -> Int -> Int
f a b c = a + b + c
g: Int -> Int
g x = x * 2
now, I'd like to create a composed function like
f(g(a), g(b), g(c))
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
elm
elm
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
edited Nov 25 '18 at 20:16
Oskar Szura
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
asked Nov 22 '18 at 8:54
Oskar SzuraOskar Szura
1,31552240
1,31552240
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
Multivariadic does not really exist in Elm. Best I can suggest is
f : Int -> Int -> Int -> Int
f a b c =
[ a, b, c ] |> List.map ((<|) g) |> List.sum
g : Int -> Int
g x =
x * 2
Note that you had an error in the type signature for g
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
Corrected, good point - as every function is curried (as I understand). Thanks for the answer.
– Oskar Szura
Nov 25 '18 at 20:17
add a comment |
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
Yes, easily:
h = flip flip g << ((<<) (<<)) << ((>>) g) << f << g
h is a <function> : number -> number -> number -> number, which is the same as h a b c = f (g a) (g b) (g c).
I think we don't need to dig deep in the correctness, since it's obvious that the version with arguments is much more readable.
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
Note thatflipwas removed fromelm/corein 0.19, so I'd be very hesitant to accept this as a proper solution! /s
– glennsl
Nov 22 '18 at 15:14
thanks for the note aboutflip. my point in the answer is that it's possible to compose the functions in order to achieve the desired result, but it makes no sense since the code becomes less readable than straight solution
– Igor Drozdov
Nov 22 '18 at 15:29
Yeah, I got that, and I'm actually pretty impressed you managed (and bothered) to figure it out. Hence the (easily missed) "/s" to indicate sarcasm on my end ;)
– glennsl
Nov 22 '18 at 15:42
So practically it's possible but there's no point of doing so... Thanks for the answer :).
– Oskar Szura
Nov 25 '18 at 20:16
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Multivariadic does not really exist in Elm. Best I can suggest is
f : Int -> Int -> Int -> Int
f a b c =
[ a, b, c ] |> List.map ((<|) g) |> List.sum
g : Int -> Int
g x =
x * 2
Note that you had an error in the type signature for g
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
Corrected, good point - as every function is curried (as I understand). Thanks for the answer.
– Oskar Szura
Nov 25 '18 at 20:17
add a comment |
Multivariadic does not really exist in Elm. Best I can suggest is
f : Int -> Int -> Int -> Int
f a b c =
[ a, b, c ] |> List.map ((<|) g) |> List.sum
g : Int -> Int
g x =
x * 2
Note that you had an error in the type signature for g
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
Corrected, good point - as every function is curried (as I understand). Thanks for the answer.
– Oskar Szura
Nov 25 '18 at 20:17
add a comment |
Multivariadic does not really exist in Elm. Best I can suggest is
f : Int -> Int -> Int -> Int
f a b c =
[ a, b, c ] |> List.map ((<|) g) |> List.sum
g : Int -> Int
g x =
x * 2
Note that you had an error in the type signature for g
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
Multivariadic does not really exist in Elm. Best I can suggest is
f : Int -> Int -> Int -> Int
f a b c =
[ a, b, c ] |> List.map ((<|) g) |> List.sum
g : Int -> Int
g x =
x * 2
Note that you had an error in the type signature for g
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
answered Nov 22 '18 at 11:55
Simon HSimon H
12.8k74477
12.8k74477
Corrected, good point - as every function is curried (as I understand). Thanks for the answer.
– Oskar Szura
Nov 25 '18 at 20:17
add a comment |
Corrected, good point - as every function is curried (as I understand). Thanks for the answer.
– Oskar Szura
Nov 25 '18 at 20:17
Corrected, good point - as every function is curried (as I understand). Thanks for the answer.
– Oskar Szura
Nov 25 '18 at 20:17
Corrected, good point - as every function is curried (as I understand). Thanks for the answer.
– Oskar Szura
Nov 25 '18 at 20:17
add a comment |
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
Yes, easily:
h = flip flip g << ((<<) (<<)) << ((>>) g) << f << g
h is a <function> : number -> number -> number -> number, which is the same as h a b c = f (g a) (g b) (g c).
I think we don't need to dig deep in the correctness, since it's obvious that the version with arguments is much more readable.
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
Note thatflipwas removed fromelm/corein 0.19, so I'd be very hesitant to accept this as a proper solution! /s
– glennsl
Nov 22 '18 at 15:14
thanks for the note aboutflip. my point in the answer is that it's possible to compose the functions in order to achieve the desired result, but it makes no sense since the code becomes less readable than straight solution
– Igor Drozdov
Nov 22 '18 at 15:29
Yeah, I got that, and I'm actually pretty impressed you managed (and bothered) to figure it out. Hence the (easily missed) "/s" to indicate sarcasm on my end ;)
– glennsl
Nov 22 '18 at 15:42
So practically it's possible but there's no point of doing so... Thanks for the answer :).
– Oskar Szura
Nov 25 '18 at 20:16
add a comment |
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
Yes, easily:
h = flip flip g << ((<<) (<<)) << ((>>) g) << f << g
h is a <function> : number -> number -> number -> number, which is the same as h a b c = f (g a) (g b) (g c).
I think we don't need to dig deep in the correctness, since it's obvious that the version with arguments is much more readable.
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
Note thatflipwas removed fromelm/corein 0.19, so I'd be very hesitant to accept this as a proper solution! /s
– glennsl
Nov 22 '18 at 15:14
thanks for the note aboutflip. my point in the answer is that it's possible to compose the functions in order to achieve the desired result, but it makes no sense since the code becomes less readable than straight solution
– Igor Drozdov
Nov 22 '18 at 15:29
Yeah, I got that, and I'm actually pretty impressed you managed (and bothered) to figure it out. Hence the (easily missed) "/s" to indicate sarcasm on my end ;)
– glennsl
Nov 22 '18 at 15:42
So practically it's possible but there's no point of doing so... Thanks for the answer :).
– Oskar Szura
Nov 25 '18 at 20:16
add a comment |
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
Yes, easily:
h = flip flip g << ((<<) (<<)) << ((>>) g) << f << g
h is a <function> : number -> number -> number -> number, which is the same as h a b c = f (g a) (g b) (g c).
I think we don't need to dig deep in the correctness, since it's obvious that the version with arguments is much more readable.
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
how to use << and >> operators to achieve that? Is it even possible to compose multivariadic functions?
Yes, easily:
h = flip flip g << ((<<) (<<)) << ((>>) g) << f << g
h is a <function> : number -> number -> number -> number, which is the same as h a b c = f (g a) (g b) (g c).
I think we don't need to dig deep in the correctness, since it's obvious that the version with arguments is much more readable.
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
answered Nov 22 '18 at 14:03
Igor DrozdovIgor Drozdov
12k52444
12k52444
Note thatflipwas removed fromelm/corein 0.19, so I'd be very hesitant to accept this as a proper solution! /s
– glennsl
Nov 22 '18 at 15:14
thanks for the note aboutflip. my point in the answer is that it's possible to compose the functions in order to achieve the desired result, but it makes no sense since the code becomes less readable than straight solution
– Igor Drozdov
Nov 22 '18 at 15:29
Yeah, I got that, and I'm actually pretty impressed you managed (and bothered) to figure it out. Hence the (easily missed) "/s" to indicate sarcasm on my end ;)
– glennsl
Nov 22 '18 at 15:42
So practically it's possible but there's no point of doing so... Thanks for the answer :).
– Oskar Szura
Nov 25 '18 at 20:16
add a comment |
Note thatflipwas removed fromelm/corein 0.19, so I'd be very hesitant to accept this as a proper solution! /s
– glennsl
Nov 22 '18 at 15:14
thanks for the note aboutflip. my point in the answer is that it's possible to compose the functions in order to achieve the desired result, but it makes no sense since the code becomes less readable than straight solution
– Igor Drozdov
Nov 22 '18 at 15:29
Yeah, I got that, and I'm actually pretty impressed you managed (and bothered) to figure it out. Hence the (easily missed) "/s" to indicate sarcasm on my end ;)
– glennsl
Nov 22 '18 at 15:42
So practically it's possible but there's no point of doing so... Thanks for the answer :).
– Oskar Szura
Nov 25 '18 at 20:16
Note that
flip was removed from elm/core in 0.19, so I'd be very hesitant to accept this as a proper solution! /s– glennsl
Nov 22 '18 at 15:14
Note that
flip was removed from elm/core in 0.19, so I'd be very hesitant to accept this as a proper solution! /s– glennsl
Nov 22 '18 at 15:14
thanks for the note about
flip. my point in the answer is that it's possible to compose the functions in order to achieve the desired result, but it makes no sense since the code becomes less readable than straight solution– Igor Drozdov
Nov 22 '18 at 15:29
thanks for the note about
flip. my point in the answer is that it's possible to compose the functions in order to achieve the desired result, but it makes no sense since the code becomes less readable than straight solution– Igor Drozdov
Nov 22 '18 at 15:29
Yeah, I got that, and I'm actually pretty impressed you managed (and bothered) to figure it out. Hence the (easily missed) "/s" to indicate sarcasm on my end ;)
– glennsl
Nov 22 '18 at 15:42
Yeah, I got that, and I'm actually pretty impressed you managed (and bothered) to figure it out. Hence the (easily missed) "/s" to indicate sarcasm on my end ;)
– glennsl
Nov 22 '18 at 15:42
So practically it's possible but there's no point of doing so... Thanks for the answer :).
– Oskar Szura
Nov 25 '18 at 20:16
So practically it's possible but there's no point of doing so... Thanks for the answer :).
– Oskar Szura
Nov 25 '18 at 20:16
add a comment |
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