i really like this example from heftia
![prog :: IO ()
prog = runEff . runLog . runSpan $ do
span "example program" do
log "foo"
span "greeting" do
log "hello"
log "world"
log "bar"
>>> prog
[Start span 'example program']
[LOG] foo
[Start span 'greeting']
[LOG] hello
[LOG] world
[End span 'greeting']
[LOG] bar
[End span 'example program']](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:yljaphrlqlnwolprgrrkr5yp/bafkreicmxzs7byhahvxobsyn55p73fwf45k6qckhs47x5cbgnp2vj7iiaq@jpeg)
December 27, 2024 at 6:40 PM
i really like this example from heftia
TIL a purely functional double-ended queue with worst-case constant time access to either end is possible and that listing monads explicitly in such a data structure can improve the time complexity of certain operations (such as list concatenation) by changing assoc. of (>>=)
December 27, 2024 at 5:50 PM
TIL a purely functional double-ended queue with worst-case constant time access to either end is possible and that listing monads explicitly in such a data structure can improve the time complexity of certain operations (such as list concatenation) by changing assoc. of (>>=)
TIL §§ (sections) is the plural of § (section)
December 24, 2024 at 3:13 PM
TIL §§ (sections) is the plural of § (section)
Reposted by buster
Reposted by buster
@wunidz.bsky.social here ya go. Not the easiest on the eyes but it's what I could make
drive.google.com/file/d/1udxh...
drive.google.com/file/d/1udxh...
result.mp4
drive.google.com
December 21, 2024 at 9:40 PM
@wunidz.bsky.social here ya go. Not the easiest on the eyes but it's what I could make
drive.google.com/file/d/1udxh...
drive.google.com/file/d/1udxh...
i feel so sad when a fellow man says “there are no femcels,” because that means he’s not often had the experience of girls-you’ve-just-met trying to cling onto him and do weird “cutesy” things hoping it’ll actually make them look cute. i always wonder if/how they get bf at all
December 22, 2024 at 1:13 AM
i feel so sad when a fellow man says “there are no femcels,” because that means he’s not often had the experience of girls-you’ve-just-met trying to cling onto him and do weird “cutesy” things hoping it’ll actually make them look cute. i always wonder if/how they get bf at all
can anyone explain how this works?
![-- | a mysterious module that apparently samples points on the face of a coid
module Face (facepoints, dbgcountfacepoints, dbgdesmos) where
import Control.Lens hiding (index)
import Data.Functor.Rep
import Data.Ix (range)
import Data.List (intercalate)
import Linear.V3
import Text.Printf
-- | retrieve the points on the faces of a cuboid
-- normal to a certain direction (sig: {-1, 0, 1}) from said cuboid
facepoints :: V3 Int -> V3 Int -> [V3 Int]
facepoints coid sig =
let (!) = index
-- p, q, r: dimensions
-- ps: list of points to sample (?)
-- h: permutation of a V3
rule p q r ps h
| sig ! p == 0 = []
| otherwise =
[ let a = if i >= coid ! r then coid ! r else i
b = if j >= coid ! q then coid ! q else j
c = if sig ! p < 0 then 0 else coid ! p
in h do V3 a b c
| (i, j) <- ps
]
-- this thing is a total mystery to me
st i -- compute starting / ending points for the face (?) in dimension i
| sig ! i < 0 = (1, 0)
| sig ! i > 0 = (0, 1)
| otherwise = (0, 0)
h0 (V3 a b c) = V3 c b a
h1 (V3 a b c) = V3 b c a
h2 (V3 a b c) = V3 b a c
p0 =
let (sj, ej) = st ey
(si, ei) = st ez
in range ((si, sj), (coid ! ez - ei, coid ! ey - ej))
p1 =
let (sj, ej) = st ez
in range ((sj, 0), (coid ! ez - ej, coid ! ex))
p2 = range ((0, 0), (coid ! ey, coid ! ex))
in concat
[ rule ex ey ez p0 h0,
rule ey ex ez p1 h1,
rule ez ex ey p2 h2
]
-- | print a list of vectors in a format that can be copy-pasted into Desmos
dbgdesmos :: (Show a) => [V3 a] -> String
dbgdesmos vs = "[" ++ intercalate "," (f <$> vs) ++ "]"
where
f (V3 x y z) = printf "(%s,%s,%s)" (show x) (show y) (show z)
-- | predict the number of points sampled by 'facepoints'
dbgcountfacepoints :: V3 Int -> V3 Int -> Int
dbgcountfacepoints ((+ pu…](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:yljaphrlqlnwolprgrrkr5yp/bafkreidovanjhfb3ijpewimigsecbe2kfm5pbcpo2z5ordtu76rixtjnjy@jpeg)
December 21, 2024 at 10:39 PM
can anyone explain how this works?
Reposted by buster
undefined behavior can really do anything
December 21, 2024 at 4:59 AM
undefined behavior can really do anything
what is so “least” about a least fixed point? in what order?
December 21, 2024 at 1:39 AM
what is so “least” about a least fixed point? in what order?
DDA line drawing algorithm, dimension-independent, lazy, infinite
original algorithm is from Wikipedia (for 2D, in C)
image: magnified image output, (0, 0) to (10, 5)
original algorithm is from Wikipedia (for 2D, in C)
image: magnified image output, (0, 0) to (10, 5)
![-- | the DDA line drawing algorithm
-- (dimension-independent, lazy, infinite)
--
-- you can generate an infinite ray by
-- ignoring the number of steps
--
-- algorithm is due to Wikipedia
dda ::
forall f i s.
(Traversable f, MonadZip f, Integral i) =>
-- | The starting point
f i ->
-- | The ending point
f i ->
-- | The number of steps (points) to get to the end
-- and the points
ST s (i, [f i])
dda start end = do
let fi = fromIntegral :: i -> Double
difference = liftM2 (-) end start
steps = maximum $ abs <$> difference
step = ((/ fi steps) . fi) <$> difference
v <- newSTRef `traverse` fmap fi start
(succ steps,) <$> fix \loop -> do
v' <- traverse readSTRef v
forM_ (mzip v step) \(r, s) -> modifySTRef r (+ s)
(fmap round v' :) <$> loop -- lazy list](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:yljaphrlqlnwolprgrrkr5yp/bafkreiewnazcxo4362h4nyiattjuhs5bvpkbprlf4fyxh42oerahn5gv7a@jpeg)
December 20, 2024 at 8:49 PM
DDA line drawing algorithm, dimension-independent, lazy, infinite
original algorithm is from Wikipedia (for 2D, in C)
image: magnified image output, (0, 0) to (10, 5)
original algorithm is from Wikipedia (for 2D, in C)
image: magnified image output, (0, 0) to (10, 5)
to build a list in the correct order in Haskell, choose one of three ways:
1. use a writer monad
2. build it in the reverse order, and then reverse it back
3. instead of using a list as an accumulator, use a function of type (a -> [a]) as the accumulator.
1. use a writer monad
2. build it in the reverse order, and then reverse it back
3. instead of using a list as an accumulator, use a function of type (a -> [a]) as the accumulator.
December 20, 2024 at 5:41 PM
to build a list in the correct order in Haskell, choose one of three ways:
1. use a writer monad
2. build it in the reverse order, and then reverse it back
3. instead of using a list as an accumulator, use a function of type (a -> [a]) as the accumulator.
1. use a writer monad
2. build it in the reverse order, and then reverse it back
3. instead of using a list as an accumulator, use a function of type (a -> [a]) as the accumulator.
the usefulness of MultiWayIf in Haskell programming cannot be overstated
(but you could hack it using case () of _ | condition1 -> expression1; _ | condition2 -> expression2; ...)
(but you could hack it using case () of _ | condition1 -> expression1; _ | condition2 -> expression2; ...)
December 20, 2024 at 5:08 PM
the usefulness of MultiWayIf in Haskell programming cannot be overstated
(but you could hack it using case () of _ | condition1 -> expression1; _ | condition2 -> expression2; ...)
(but you could hack it using case () of _ | condition1 -> expression1; _ | condition2 -> expression2; ...)
“is this object oriented mathematics?”
December 20, 2024 at 4:25 PM
“is this object oriented mathematics?”
fuck the gang of four, stand edward kmett… seriously
December 20, 2024 at 4:10 PM
fuck the gang of four, stand edward kmett… seriously
if you have an array with four (4) elements -- a product type -- then its index could be one of four (4) choices -- a sum type
indexing is to logarithms as functions are to exponentials
indexing is to logarithms as functions are to exponentials
December 20, 2024 at 3:02 AM
if you have an array with four (4) elements -- a product type -- then its index could be one of four (4) choices -- a sum type
indexing is to logarithms as functions are to exponentials
indexing is to logarithms as functions are to exponentials
Reposted by buster
at santa-scale it probably has to be done by separate nodes in a distributed system
December 18, 2024 at 10:26 PM
at santa-scale it probably has to be done by separate nodes in a distributed system
there's a whole community on the internet accumulating knowledge about teaching, metathinking and problem solving
amazing
amazing
December 20, 2024 at 1:21 AM
there's a whole community on the internet accumulating knowledge about teaching, metathinking and problem solving
amazing
amazing
when i was 22, i was rotting in bed
when Twan van Laarhoven was 22, he published in a blog post an innovation that would be later named after himself ... van Laarhoven lenses
also, scary to think that he's nearly 40 now
time flies like a banana
fruit flies like an arrow
when Twan van Laarhoven was 22, he published in a blog post an innovation that would be later named after himself ... van Laarhoven lenses
also, scary to think that he's nearly 40 now
time flies like a banana
fruit flies like an arrow
December 20, 2024 at 12:27 AM
when i was 22, i was rotting in bed
when Twan van Laarhoven was 22, he published in a blog post an innovation that would be later named after himself ... van Laarhoven lenses
also, scary to think that he's nearly 40 now
time flies like a banana
fruit flies like an arrow
when Twan van Laarhoven was 22, he published in a blog post an innovation that would be later named after himself ... van Laarhoven lenses
also, scary to think that he's nearly 40 now
time flies like a banana
fruit flies like an arrow
Reposted by buster
If one has to use CPP in Haskell, doing it in the cabal file as a way to conditionally include modules instead of sprinkling #ifdef/#endif across the code-base feels much cleaner to me. A small amount of code duplication is better than slicing and dicing code to the point it becomes unreadable.
December 18, 2024 at 5:49 PM
If one has to use CPP in Haskell, doing it in the cabal file as a way to conditionally include modules instead of sprinkling #ifdef/#endif across the code-base feels much cleaner to me. A small amount of code duplication is better than slicing and dicing code to the point it becomes unreadable.
