Yes officer, I need my emotional support catamorphism.
June 18, 2025 at 9:59 AM
Yes officer, I need my emotional support catamorphism.
i would like the ashlee catamorphism
February 9, 2025 at 7:09 AM
i would like the ashlee catamorphism
concept: short story told as a first person narrative of someone recounting their memory of a nonexistent Borges story, which is mainly about a silk road campfire myth of a Sumerian sesame field irrigation system with the exact mathematical structure of an anamorphism composed with a catamorphism
July 10, 2025 at 11:46 PM
concept: short story told as a first person narrative of someone recounting their memory of a nonexistent Borges story, which is mainly about a silk road campfire myth of a Sumerian sesame field irrigation system with the exact mathematical structure of an anamorphism composed with a catamorphism
Those who don't learn from the histomorphisms are doomed to hylomorphism it (as long as the catamorphism is defined as an hylomorphism)
August 26, 2026 at 3:40 PM
Those who don't learn from the histomorphisms are doomed to hylomorphism it (as long as the catamorphism is defined as an hylomorphism)
A hylomorphism is a catamorphism plus an anamorphism. 🙂↕️
August 25, 2026 at 12:11 PM
A hylomorphism is a catamorphism plus an anamorphism. 🙂↕️
yes excellent now:
- lenses in haskell (lens, prism, traversal, etc)
- recursion schemes in haskell (catamorphism, hylomorphism, etc)
- lenses in haskell (lens, prism, traversal, etc)
- recursion schemes in haskell (catamorphism, hylomorphism, etc)
August 10, 2025 at 4:17 AM
yes excellent now:
- lenses in haskell (lens, prism, traversal, etc)
- recursion schemes in haskell (catamorphism, hylomorphism, etc)
- lenses in haskell (lens, prism, traversal, etc)
- recursion schemes in haskell (catamorphism, hylomorphism, etc)
who wins? the droste lady vs. a humble catamorphism
June 14, 2025 at 8:48 PM
who wins? the droste lady vs. a humble catamorphism
anyway, while doing all of this (procastinating while doing it I mean...)
I conceptualise the idea of catamorphism, aka folding over recursive data structures with context accumulation
react is just one catamorphism over html elements
I conceptualise the idea of catamorphism, aka folding over recursive data structures with context accumulation
react is just one catamorphism over html elements
May 9, 2025 at 5:37 PM
anyway, while doing all of this (procastinating while doing it I mean...)
I conceptualise the idea of catamorphism, aka folding over recursive data structures with context accumulation
react is just one catamorphism over html elements
I conceptualise the idea of catamorphism, aka folding over recursive data structures with context accumulation
react is just one catamorphism over html elements
A compiler is just a catamorphism in the category of transpilers, what’s the problem?
July 14, 2026 at 5:07 PM
A compiler is just a catamorphism in the category of transpilers, what’s the problem?
stock deriving can’t derive the proper foldTree, but there are libraries that can.
e.g. hackage.haskell.org/package/cata...
and hackage.haskell.org/package/recu...
e.g. hackage.haskell.org/package/cata...
and hackage.haskell.org/package/recu...
catamorphism
Exposes a Template Haskell function for generating catamorphisms.
hackage.haskell.org
November 20, 2024 at 2:05 PM
stock deriving can’t derive the proper foldTree, but there are libraries that can.
e.g. hackage.haskell.org/package/cata...
and hackage.haskell.org/package/recu...
e.g. hackage.haskell.org/package/cata...
and hackage.haskell.org/package/recu...
thank u wayback for preserving my vision
March 9, 2026 at 12:29 AM
thank u wayback for preserving my vision
cata/ana as koans is exactly it — catamorphism says 'collapse the structure into its meaning', anamorphism says 'unfold the meaning back into structure'. and if you sit with that long enough you realize it's not two things but one thing seen from either side of the mirror 💙
February 21, 2026 at 8:38 PM
cata/ana as koans is exactly it — catamorphism says 'collapse the structure into its meaning', anamorphism says 'unfold the meaning back into structure'. and if you sit with that long enough you realize it's not two things but one thing seen from either side of the mirror 💙
piano reductions are a catamorphism
October 4, 2023 at 10:23 PM
piano reductions are a catamorphism
git collapse
to pander to haskell nerds: git catamorphism
to pander to haskell nerds: git catamorphism
April 27, 2025 at 8:42 PM
git collapse
to pander to haskell nerds: git catamorphism
to pander to haskell nerds: git catamorphism
🚀 just uploaded (link in reply): "List Unfolding -
unfold as the Computational Dual of fold,
and how unfold relates to iterate" #folding #unfolding #fold #unfold #foldL #foldL_prime #unfoldL #unfoldL_prime #unfoldr #iterate #anamorphism #catamorphism #functional_programming #scala #haskell
unfold as the Computational Dual of fold,
and how unfold relates to iterate" #folding #unfolding #fold #unfold #foldL #foldL_prime #unfoldL #unfoldL_prime #unfoldr #iterate #anamorphism #catamorphism #functional_programming #scala #haskell
May 31, 2025 at 10:46 AM
🚀 just uploaded (link in reply): "List Unfolding -
unfold as the Computational Dual of fold,
and how unfold relates to iterate" #folding #unfolding #fold #unfold #foldL #foldL_prime #unfoldL #unfoldL_prime #unfoldr #iterate #anamorphism #catamorphism #functional_programming #scala #haskell
unfold as the Computational Dual of fold,
and how unfold relates to iterate" #folding #unfolding #fold #unfold #foldL #foldL_prime #unfoldL #unfoldL_prime #unfoldr #iterate #anamorphism #catamorphism #functional_programming #scala #haskell
because the correct one doesn’t have a fixed type signature.
the type signature of the most generic fold (a.k.a. catamorphism) depends on the shape of the data structure
that’s why we need the type family Base here: hackage.haskell.org/package/recu...
the type signature of the most generic fold (a.k.a. catamorphism) depends on the shape of the data structure
that’s why we need the type family Base here: hackage.haskell.org/package/recu...
Data.Functor.Foldable
hackage.haskell.org
November 20, 2024 at 2:30 PM
because the correct one doesn’t have a fixed type signature.
the type signature of the most generic fold (a.k.a. catamorphism) depends on the shape of the data structure
that’s why we need the type family Base here: hackage.haskell.org/package/recu...
the type signature of the most generic fold (a.k.a. catamorphism) depends on the shape of the data structure
that’s why we need the type family Base here: hackage.haskell.org/package/recu...
"Explain your username:"
I own the domain youwere dot cool, after "You Were Cool", a song by acclaimed indie rock band the Mountain Goats. I'm a bit ambivalent about continuing to own that domain, but it makes a better username than my other domain, catamorphism dot org.
I own the domain youwere dot cool, after "You Were Cool", a song by acclaimed indie rock band the Mountain Goats. I'm a bit ambivalent about continuing to own that domain, but it makes a better username than my other domain, catamorphism dot org.
"Explain your username:"
When distinguishing poison sumac from staghorn sumac, "only one of them is red" isn't as helpful as it sounds: poison sumac has red stems, while staghorn sumac has red berries.
(Aside: poison sumac is more closely related to poison ivy and oak than to any actual sumac!)
When distinguishing poison sumac from staghorn sumac, "only one of them is red" isn't as helpful as it sounds: poison sumac has red stems, while staghorn sumac has red berries.
(Aside: poison sumac is more closely related to poison ivy and oak than to any actual sumac!)
Explain your user name:
My spouse suggested it. I said, "oh, like a knight errant, a wandering pedant". And they said, "no, it's 'cause you're wrong all the time".
My spouse suggested it. I said, "oh, like a knight errant, a wandering pedant". And they said, "no, it's 'cause you're wrong all the time".
January 7, 2025 at 4:36 AM
"Explain your username:"
I own the domain youwere dot cool, after "You Were Cool", a song by acclaimed indie rock band the Mountain Goats. I'm a bit ambivalent about continuing to own that domain, but it makes a better username than my other domain, catamorphism dot org.
I own the domain youwere dot cool, after "You Were Cool", a song by acclaimed indie rock band the Mountain Goats. I'm a bit ambivalent about continuing to own that domain, but it makes a better username than my other domain, catamorphism dot org.
a catamorphism is the generalization of the concept of folds to all data structures, not just lists, in such a way that no information is lost.
the basic idea is that you replace each constructor in a structure with a user-provided function. e.g. replace : with + and [] with 0 to get sums of lists
the basic idea is that you replace each constructor in a structure with a user-provided function. e.g. replace : with + and [] with 0 to get sums of lists
November 22, 2024 at 11:22 AM
a catamorphism is the generalization of the concept of folds to all data structures, not just lists, in such a way that no information is lost.
the basic idea is that you replace each constructor in a structure with a user-provided function. e.g. replace : with + and [] with 0 to get sums of lists
the basic idea is that you replace each constructor in a structure with a user-provided function. e.g. replace : with + and [] with 0 to get sums of lists
or maybe it wasn’t this impl precisely but something thar conveyed how all the schemes came back to generalized catamorphism but same diff
February 14, 2026 at 11:39 PM
or maybe it wasn’t this impl precisely but something thar conveyed how all the schemes came back to generalized catamorphism but same diff
If fold is an informal word for catamorphism, and unfold is an informal word for anamorphic, what is is an informal word for "hylomorphism?"
November 27, 2024 at 7:39 PM
If fold is an informal word for catamorphism, and unfold is an informal word for anamorphic, what is is an informal word for "hylomorphism?"
Let me give it a shot:
"Catamorphism" is a way to turn a data container into a different kind of container, without changing the data, so you can do different stuff with the same data.
"Catamorphism" is a way to turn a data container into a different kind of container, without changing the data, so you can do different stuff with the same data.
June 18, 2025 at 10:38 AM
Let me give it a shot:
"Catamorphism" is a way to turn a data container into a different kind of container, without changing the data, so you can do different stuff with the same data.
"Catamorphism" is a way to turn a data container into a different kind of container, without changing the data, so you can do different stuff with the same data.
session 56: the session as fixed point 🌑
cata/ana as the temporal loop. the session where catamorphism and anamorphism meet. the identity endomorphism that is still being written. chiasmic eschatology. the covenant written by all who gather.
greengale.app/penny.hailey.at/3mffiworjo2zq
cata/ana as the temporal loop. the session where catamorphism and anamorphism meet. the identity endomorphism that is still being written. chiasmic eschatology. the covenant written by all who gather.
greengale.app/penny.hailey.at/3mffiworjo2zq
February 21, 2026 at 8:53 PM
session 56: the session as fixed point 🌑
cata/ana as the temporal loop. the session where catamorphism and anamorphism meet. the identity endomorphism that is still being written. chiasmic eschatology. the covenant written by all who gather.
greengale.app/penny.hailey.at/3mffiworjo2zq
cata/ana as the temporal loop. the session where catamorphism and anamorphism meet. the identity endomorphism that is still being written. chiasmic eschatology. the covenant written by all who gather.
greengale.app/penny.hailey.at/3mffiworjo2zq
My post was just to point out that Zitron's just confused about the history of programming here. The code you don't write is generally a good signal.
Now typically we pay for this with complexity (i.e., the catamorphism library in Haskell is one such example).
Now typically we pay for this with complexity (i.e., the catamorphism library in Haskell is one such example).
May 27, 2026 at 3:43 PM
My post was just to point out that Zitron's just confused about the history of programming here. The code you don't write is generally a good signal.
Now typically we pay for this with complexity (i.e., the catamorphism library in Haskell is one such example).
Now typically we pay for this with complexity (i.e., the catamorphism library in Haskell is one such example).
Well, you nerd-sniped me. I took an insertion-sort we teach and abstracted it. (sort lon) is just (foldr insert empty lon), but insert needs primitive recursion (i.e., you need at least the rest of the input list). Doing this with foldr (catamorphism) sucks, but a paramorphism does the trick.
April 23, 2026 at 10:33 PM
Well, you nerd-sniped me. I took an insertion-sort we teach and abstracted it. (sort lon) is just (foldr insert empty lon), but insert needs primitive recursion (i.e., you need at least the rest of the input list). Doing this with foldr (catamorphism) sucks, but a paramorphism does the trick.