Add space-invaders

Author: meooow25

Diff for: default/space-invaders/Import.hs

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+module Import (module X) where
+import Data.Bits as X
+import Data.List as X
+import Control.Concurrent as X
+import System.IO as X
+import Data.Bool as X

Diff for: default/space-invaders/README.md

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+# space-invaders
+
+A vastly inferior version of the classic
+[Space Invaders](https://en.wikipedia.org/wiki/Space_Invaders).
+
+## How to play
+
+Use `runghc space-invaders.hs` to run the game. Tested with GHC 9.2.5.
+
+![](game.png)
+
+Press <kbd>a</kbd> to move left, <kbd>d</kbd> to move right, and
+<kbd>Space</kbd> to shoot. You win if you destroy all the aliens. You lose if
+you get hit by an alien or the aliens reach the row in front of you.
+
+## Implementation
+
+Nothing too unusual. The game state consists of a time counter, the movement
+direction of the aliens, the position of the player, the positions of the
+player's bullet, the positions of the aliens' bullets, and the positions of the
+aliens. A loop transforms the state with optional user input, draws the state,
+sleeps for a while, and repeats.
+
+Here is the same code, with better names and formatting:
+
+```hs
+import Control.Concurrent (threadDelay)
+import Data.Bits (xor)
+import Data.Bool (bool)
+import Data.List ((\\), elemIndex, intersect)
+import System.IO (hSetBuffering, stdin, hReady, BufferMode(..)) 
+
+divides :: Int -> Int -> Bool -- !
+divides x y = mod y x == 0
+
+input :: IO Char -- i
+input = hReady stdin >>= bool (pure '.') (getChar <* input)
+
+type V2 = (Int, Int)
+
+plus :: V2 -> V2 -> V2 -- p
+plus (i,j) (i',j') = (i+i', j+j')
+
+type Board = V2 -> Char
+
+setChar :: Char -> V2 -> Board -> Board -- u
+setChar c p b q = bool (b q) c (p == q)
+
+-- Board size is 10x35
+h, w :: [Int]
+h = [0..9]
+w = [0..34]
+
+keep :: [V2] -> [V2] -- k
+keep = intersect $ (,) <$> h <*> w
+
+clamp :: V2 -> V2 -- c
+clamp (i,j) = (min 9 $ max 0 i, min 34 $ max 0 j)
+
+loop :: Int -> Int -> V2 -> [V2] -> [V2] -> [V2] -> IO a -- l
+loop time{-t-} dir{-d-} plr{-s-} plrBlt{-b-} alienBlts{-v-} aliens{-a-}
+  | null aliens = error "WIN"
+  | or [True | (7,_) <- aliens] || elem plr alienBlts = error "LOSE"
+  | otherwise = do
+    c <- input
+    let -- Move the player based on input
+        plr2 = clamp $ plus (0, maybe 0 (1-) $ elemIndex c "d a") plr
+
+        -- Move the aliens
+        aliens2 = plus (0, bool 0 dir $ 10 `divides` time) <$> aliens
+        aliens3 = plus (1,0) <$> aliens
+        (aliens4, dir2) = bool (aliens3, -dir) (aliens2, dir) (aliens2 == keep aliens2)
+
+        -- Move the player bullet or spawn one based on input
+        plrBlt2 = keep $ map (plus (-1,0)) $ bool plrBlt [plr] $ c == ' ' && null plrBlt
+
+        -- Remove hit aliens
+        aliens5 = aliens4 \\ plrBlt2
+
+        -- Move the alien bullets and spawn new ones
+        alienBlts2 = keep $ [z | z@(i,j) <- aliens5, 307 `divides` (97*i `xor` 97*j `xor` time)]
+                            ++ map (plus (mod time 2, 0)) alienBlts
+
+        -- Draw the board
+        board = foldr (setChar '*')
+                      (foldr (setChar 'W')
+                            (foldr (setChar 'v')
+                                    (setChar 'A' plr2 (const ' '))
+                                    alienBlts2)
+                              aliens5)
+                      plrBlt2
+    putStrLn $ "\ESC[H" ++ unlines [[board (i,j) | j <- w] ++ "\ESC[K" | i <- h] ++ "\ESC[J"
+    threadDelay $ 9^5
+    loop (time+1) dir2 plr2 (plrBlt2 \\ aliens4) alienBlts2 aliens5
+
+main :: IO ()
+main = do
+  hSetBuffering stdin NoBuffering
+  loop 0 1 (8,15) [] [] $ (,) <$> [1,3,5] <*> [3,6..24]
+
+```
+
+One interesting part is the representation of the board as `V2 -> Char`, which
+allowed for a cute definition of `setChar`. 
+
+This has been fun!

Diff for: default/space-invaders/game.png

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+import Import;main=do{hSetBuffering stdin NoBuffering;l 0 1(8,15)[][]$(,)<$>[1,3
+,5]<*>[3,6..24]};x!y=mod y x==0;i=hReady stdin>>=y(pure '.')(getChar<*i);y=bool
+k=intersect$(,)<$>h<*>w;p(i,j)(k,l)=(i+k,j+l);u c p b q=y(b q)c(p==q);w=[0..34]
+l t d s b v a|a==[]=error"WIN"|or[0<1|(7,_)<-a]||elem s v=error"LOSE"|let=i>>=
+ \c->let{a2=p(0,y 0 d$10!t)<$>a;a3=p(1,0)<$>a;(a4,d2)=y(a3,-d)(a2,d)(a2==k a2);
+a5=a4\\b2;v2=k$[z|z@(i,j)<-a5,307!(97*i`xor`97*j`xor`t)]++map(p(mod t 2,0))v;
+s2=cl$p(0,maybe 0(1-)$elemIndex c"d a")s;b2=k$map(p(-1,0))$y b[s]$c==' '&&b==[];
+f=foldr(u '*')(foldr(u 'W')(foldr(u 'v')(u 'A's2(\_->' '))v2)a5)b2;cl(i,j)=(min
+9$max 0i,min 34$max 0j);}in do{putStrLn$"\ESC[H"++unlines[[f(i,j)|j<-w]++
+"\ESC[K"|i<-h]++"\ESC[J";threadDelay$9^5;l(t+1)d2 s2(b2\\a4)v2 a5};h=[0..9]
+-- ^10 ------------------------------------------------------------------ 80> --
+{- default-10-80/space-invaders (meooow25)
+
+GHC 9.2.5
+
+runghc space-invaders.hs
+
+a - left
+d - right
+spc - shoot
+-}