Initial data commit

Task/Probabilistic-choice/Haskell/probabilistic-choice.hs

@@ -0,0 +1,47 @@
+import System.Random (newStdGen, randomRs)
+
+dataBinCounts :: [Float] -> [Float] -> [Int]
+dataBinCounts thresholds range =
+  zipWith
+    (-)
+    (xs <> [sampleSize])
+    (0 : xs)
+  where
+    sampleSize = length range
+    xs =
+      (-) sampleSize . length
+        . flip filter range
+        . (<)
+        <$> thresholds
+
+--------------------------- TEST -------------------------
+main :: IO ()
+main = do
+  g <- newStdGen
+  let fractions = recip <$> [5 .. 11] :: [Float]
+      expected = fractions <> [1 - sum fractions]
+      actual =
+        (/ 1000000.0) . fromIntegral
+          <$> dataBinCounts
+            (scanl1 (+) expected)
+            (take 1000000 (randomRs (0, 1) g))
+      piv n x = take n (x <> repeat ' ');
+
+  putStrLn "       expected     actual"
+  mapM_ putStrLn $
+    zipWith3
+      ( \l s c ->
+          piv 7 l
+            <> (piv 13 (show s) <> piv 12 (show c))
+      )
+      [ "aleph",
+        "beth",
+        "gimel",
+        "daleth",
+        "he",
+        "waw",
+        "zayin",
+        "heth"
+      ]
+      expected
+      actual