fixpoint-combinators Questions
3
Solved
Every time I’ve used fix :: (a -> a) -> a, it’s been at the type
((a -> b) -> a -> b) -> a -> b
for some a and b. Is there actually some application of fix where its type pa...
Wines asked 20/1, 2015 at 1:8
2
Solved
A list in Haskell might look like this:
data List a = Nil | Cons a (List a)
A type theoretic interpretation is:
λα.μβ.1+αβ
which encodes the list type as the fixed point of a functor. In Hask...
Belike asked 21/3, 2014 at 22:17
4
I recently learned about Data.Function.fix, and now I want to apply it everywhere. For example, whenever I see a recursive function I want to "fix" it. So basically my question is where and when sh...
Explicative asked 10/2, 2014 at 21:15
1
Solved
After reading Milewski's F-algebra article, I tried to implement it and use for a real-world problem. However, I can't seem to figure out how to write instances for Fix,
newtype Fix f = Fx { unFix...
Daydream asked 3/1, 2014 at 2:8
2
Solved
I am new to the world of fixed-point combinators and I guess they are used to recurse on anonymous lambdas, but I haven't really got to use them, or even been able to wrap my head around them compl...
Battlefield asked 7/4, 2013 at 6:38
3
Is there a fixed point combinator for creating tuples of mutually recursive functions? I.e. I'm looking for something like the Y-Combinator but which takes multiple "recursive"* functions, and will...
Feigned asked 4/2, 2011 at 14:29
2
Solved
>>>flip fix (0 :: Int) (\a b -> putStrLn "abc")
Output: "abc"
This is a simplified version of using flip fix.
I saw this way of using it in some youtube video which are probably from ...
Cahier asked 20/3, 2013 at 12:7
2
Solved
I have a function which computes a fixed point in terms of iterate:
equivalenceClosure :: (Ord a) => Relation a -> Relation a
equivalenceClosure = fst . List.head -- "guaranteed" to exist
...
Audriaaudrie asked 9/6, 2011 at 22:52
4
Solved
Looking at the GHC source code I can see that the definition for fix is:
fix :: (a -> a) -> a
fix f = let x = f x in x
In an example fix is used like this:
fix (\f x -> let x' = x+1 in...
Tunisia asked 21/10, 2012 at 15:46
2
How can the following data type from Haskell be expressed in OCaml or SML?
newtype Fix f = In (f (Fix f))
Diction asked 21/10, 2012 at 4:43
5
Solved
The fixed point combinator doesn't always produce the right answer given the definition:
fix f = f (fix f)
The following code does not terminate:
fix (\x->x*x) 0
Of course, fix can't alway...
Stretch asked 11/11, 2011 at 20:9
1
Solved
I'm looking for a library that will compute the fixed point / closure of a set under a number of operators of variable arity. For example,
fixwith [(+)] [1]
for the integers should compute all o...
Jimmie asked 30/8, 2011 at 23:12
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