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 (>>=)
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?
undefined behavior can really do anything
December 21, 2024 at 4:59 AM
undefined behavior can really do anything
maybe i should have called 'loop' 'this' for funsies
December 20, 2024 at 8:53 PM
maybe i should have called 'loop' 'this' for funsies
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)
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?”
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
writing imperative code in haskell was a mistake
![extrapoints :: STRef s (Seq IP) <- new Seq.empty -- right-to-left, FIFO
out :: STRef s [IP] <- new []
callCC \break_ -> do
let break = break_ ()
fix \continue -> do
let tell = write out
read extrapoints >>= \case
a :<| points -> do
tell [a]
if sameblock a end
then break
else continue
_ -> pure ()
-- todo...
break](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:yljaphrlqlnwolprgrrkr5yp/bafkreic4a6mgfwt6zcyjvpouwxy3dhsmaz4homfyegem2it2rkmhmqio2q@jpeg)
December 19, 2024 at 8:00 PM
writing imperative code in haskell was a mistake
Variadic Composition
(uses the Text.Printf trick)
(language: GHC2021, no other extensions)
(uses the Text.Printf trick)
(language: GHC2021, no other extensions)
December 17, 2024 at 11:43 PM
Variadic Composition
(uses the Text.Printf trick)
(language: GHC2021, no other extensions)
(uses the Text.Printf trick)
(language: GHC2021, no other extensions)
can you find a solution to this problem? (or decide that there is not)
December 17, 2024 at 11:05 PM
can you find a solution to this problem? (or decide that there is not)
fun fact i learned. a box-box collision problem can be reduced to a ray-box collision problem
December 12, 2024 at 7:12 PM
fun fact i learned. a box-box collision problem can be reduced to a ray-box collision problem
I just completed "Historian Hysteria" - Day 1 - Advent of Code 2024 #AdventOfCode adventofcode.com/2024/day/1
December 1, 2024 at 5:03 PM
I just completed "Historian Hysteria" - Day 1 - Advent of Code 2024 #AdventOfCode adventofcode.com/2024/day/1
December 1, 2024 at 4:38 PM
Some brand names on Amazon look like randomly generated and yet manage to deliver good stuff
December 1, 2024 at 4:38 AM
Some brand names on Amazon look like randomly generated and yet manage to deliver good stuff
This week is refactoring week. I’m moving a proof of concept demo into an actual framework.
This is my movement code. I explored so many options that now I doubt I can make the code simpler. Try reading it.
This is my movement code. I explored so many options that now I doubt I can make the code simpler. Try reading it.
November 29, 2024 at 8:05 PM
This week is refactoring week. I’m moving a proof of concept demo into an actual framework.
This is my movement code. I explored so many options that now I doubt I can make the code simpler. Try reading it.
This is my movement code. I explored so many options that now I doubt I can make the code simpler. Try reading it.
Investor Marc Andreessen went on Joe Rogan Experience and said the CFPB was “debanking” people who were on the right.
His company LendUp was implicated committed a crime and the CFPB stopped it.
His company LendUp was implicated committed a crime and the CFPB stopped it.
November 29, 2024 at 4:07 PM
Investor Marc Andreessen went on Joe Rogan Experience and said the CFPB was “debanking” people who were on the right.
His company LendUp was implicated committed a crime and the CFPB stopped it.
His company LendUp was implicated committed a crime and the CFPB stopped it.
On X/Twitter they’re seriously trying to cancel CFPB, wow. The DOGE wants it gone.
November 29, 2024 at 4:03 PM
On X/Twitter they’re seriously trying to cancel CFPB, wow. The DOGE wants it gone.
I just got back access to the internet, and I fixed the sound. I was multiplying the source coordinates by an extra factor of 8. That's fixed.
November 26, 2024 at 10:35 PM
I just got back access to the internet, and I fixed the sound. I was multiplying the source coordinates by an extra factor of 8. That's fixed.
I've gotten the most basic aspect of PvP working: damage animation. But I can't get the sound to play for some reason.
A clever thing Minecraft does is the client calculates the hits, reducing the burden on the server. The server only checks if they're valid.
A clever thing Minecraft does is the client calculates the hits, reducing the burden on the server. The server only checks if they're valid.
November 20, 2024 at 12:28 AM
I've gotten the most basic aspect of PvP working: damage animation. But I can't get the sound to play for some reason.
A clever thing Minecraft does is the client calculates the hits, reducing the burden on the server. The server only checks if they're valid.
A clever thing Minecraft does is the client calculates the hits, reducing the burden on the server. The server only checks if they're valid.
Cool thing I'm working on. This is a Minecraft server being developed from scratch. I'm able to synchronize player movement. But the server doesn't understand blocks yet, so block information isn't being sent to other players.
November 19, 2024 at 5:17 PM
Cool thing I'm working on. This is a Minecraft server being developed from scratch. I'm able to synchronize player movement. But the server doesn't understand blocks yet, so block information isn't being sent to other players.