Anonymous-recursion is recursion which does not explicitly call a function by name. This is usually done by calling the current function from within itself or by passing the current function as a callback to an other (named) function. Use this tag for questions directly related to this type of recursion only.
Questions tagged [anonymous-recursion]
18 questions
27
votes
9 answers
In Scheme, how do you use lambda to create a recursive function?
I'm in a Scheme class and I was curious about writing a recursive function without using define. The main problem, of course, is that you cannot call a function within itself if it doesn't have a name.
I did find this example: It's a factorial…
NcAdams
- 2,521
- 4
- 21
- 32
8
votes
3 answers
Y combinator, Infinite types and Anonymous recursion in Haskell
I was trying to solve the maximal subsequence sum problem and came up with a neato solution
msss :: (Ord a, Num a) => [a] -> a
msss = f 0 0
f gmax _ [] = gmax
f gmax lmax (x:xs) =
let g = max (lmax + x)
in f (g gmax) (g 0) xs
You call the…
TheIronKnuckle
- 7,224
- 4
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- 56
7
votes
1 answer
Two-layer "Y-style" combinator. Is this common? Does this have an official name?
I've been looking into how languages that forbid use-before-def and don't have mutable cells (no set! or setq) can nonetheless provide recursion. I of course ran across the (famous? infamous?) Y combinator and friends,…
danfuzz
- 4,253
- 24
- 34
6
votes
7 answers
Which programming languages support functions that take themselves as arguments?
I'm doing an academic exercise (for personal growth). I want to find programming languages that allow you to define functions that are capable of accepting themselves (i.e., pointers to themselves) as arguments.
For example, in JavaScript:
function…
Joshua Wise
- 613
- 4
- 15
5
votes
5 answers
Does "Anonymous Recursion" work in .NET? It does in Mono
I surfed into this site a few days ago on "Anonymous Recursion in C#". The thrust of the article is that the following code will not work in C#:
Func fib = n => n > 1 ? fib(n - 1) + fib(n - 2) : n;
The article then goes into some detail…
Justin
- 8,853
- 4
- 42
- 42
5
votes
2 answers
The mechanism of anonymous function to call itself in Scheme?
I'm reading The Little Schemer and feel confused about the following code:
((lambda (len)
(lambda (l)
(cond
((null? l) 0)
(else
(+ 1 (len (cdr l)))))))
eternity)
(define eternity
(lambda (x)
…
liu
- 937
- 1
- 9
- 15
3
votes
2 answers
List function with Y combinator does no recursion, why?
Note: This is kind of homework, kind of not -- the end goal is to have a function that produces a powerset of a set of numbers supplied to the function as a list of numbers. I have a recursive version of the function but I now need to find some ways…
David
- 113
- 3
- 8
3
votes
3 answers
Generating powerset in one function, no explicit recursion, and using only simplest primitives in Racket
Note: this is a bonus for homework, but I have spent way too long on trying things to no avail. Help is much appreciated, but not necessary I suppose.
Premise:
generate a powerset for a list of numbers, but without using any helpers, explicit…
user12781491
3
votes
1 answer
Howto: "letrec" in C# (lambda expression call within its definition)
Consider the factorial function defined within a method body as a lambda expression and assigned to a variable:
Func factfail = n =>
{
if (n == 0)
return 1;
else
return n * factfail(n-1);
};
This fails, since…
Sebastian Gregor
- 345
- 2
- 11
3
votes
2 answers
Little Schemer: write function that only supports lists of length ≤ 2
In the book The little schemer, we find this function that only supports lists with length smaller than or equal to 1:
(((lambda (mk-length) ; A.
(mk-length mk-length))
(lambda (mk-length)
(lambda (l)
…
jiamo
- 1,406
- 1
- 17
- 29
2
votes
2 answers
Little Schemer: why wrap (mk-length mk-length) into a function?
In The Little Schemer book, in Chapter 9, while building a length function for arbitrary long input, the following is suggested (on pages 170-171), that in the following code snippet (from page 168 itself):
((lambda (mk-length)
(mk-length…
user8554766
2
votes
1 answer
How to do this length≤1 more than once?
I've spent a day reading page 166's length≤1 in the book The Little Schemer; there's the following code:
(((lambda (mk-length)
(mk-length mk-length))
(lambda (mk-length)
(lambda (l)
(cond
((null? l) 0)
(else (add1
…
abelard2008
- 1,984
- 1
- 20
- 35
1
vote
4 answers
Recursion with anonymous function
Possible Duplicates:
javascript: recursive anonymous function?
Anonymous recursive PHP functions
I was wondering... Is it possible to do recursion with anonymous function?
Here is one example: I need to get six-chars long string which may contain…
daGrevis
- 21,014
- 37
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- 139
1
vote
1 answer
Call By Need in Scheme
I have this code knowing that parameters are passed using call by need:
(define fact-2
(let ((foo (lambda (n f)
(if (zero? n)
1
(f n f)))))
(lambda (n)
(let ((res 1))
(foo n…
Maya Saias
- 37
- 9
1
vote
1 answer
C# anonymous recursion and Y-combinator performance
Below are are functions and tests of anonymous recursion. The first one is true Y-combinator, looks fine and simple, but is quite slow. It takes 1000ms to execute 1 mln iterations. The second is quite ugly because of c(c,item) but works twice faster…
user448516