commit 321df82944ddfa03edbfa456d6d5c73a0a90f1de
Author: Danila Fedorin <danila.fedorin@gmail.com>
Date:   Mon May 4 16:49:54 2020 -0700

    Write up initial Cow DSL.

diff --git a/src/Cdl/Cow.hs b/src/Cdl/Cow.hs
new file mode 100644
index 0000000..3abbc20
--- /dev/null
+++ b/src/Cdl/Cow.hs
@@ -0,0 +1,99 @@
+module Cdl.Cow where
+import Control.Monad.State
+import Data.Fixed
+import Data.List
+
+data Coord = Coord
+    { longitude :: Float
+    , latitude :: Float
+    }
+
+data CowState = CowState
+    { id :: Int
+    , samplingFrequency :: Float
+    , movementSpeed :: Float
+    , movementDirection :: Float
+    , position :: Coord
+    , time :: Float
+    , dataPoints :: [Coord]
+    }
+
+type CowBehavior = State CowState
+
+type Collar = (Int, Float, Coord, CowBehavior ())
+type DataPoint = (Int, Coord)
+
+emitPoint :: Coord -> CowBehavior ()
+emitPoint c = modify (\s -> s { dataPoints = c : dataPoints s })
+
+setPosition :: Coord -> CowBehavior ()
+setPosition c = modify (\s -> s { position = c })
+
+setDirection :: Float -> CowBehavior ()
+setDirection d = modify (\s -> s { movementDirection = d })
+
+increaseTime :: Float -> CowBehavior ()
+increaseTime t = modify (\s -> s { time = time s + t })
+
+repeatUntil :: (CowState -> Bool) -> CowBehavior a -> CowBehavior a
+repeatUntil p m = ((,) <$> m <*> gets p) >>= (\(a,b) -> if b then return a else m)
+
+repeatTimes :: Int -> CowBehavior a -> CowBehavior ()
+repeatTimes n m = sequence_ $ replicate n m
+
+addOffset :: (Float, Float) -> Coord -> Coord
+addOffset (x, y) c = Coord (longitude c + longitudeDelta) (latitude c + latitudeDelta)
+    where
+        latitudeDelta = y / 111111
+        longitudeDelta = x / (111111 * cos (latitude c))
+
+samplingDeltas :: Float -> CowBehavior [Float]
+samplingDeltas t = do
+    currentTime <- gets time
+    frequency <- gets samplingFrequency
+    let firstDelta = (frequency * fromIntegral (ceiling (currentTime/frequency))) - currentTime
+    return $ takeWhile (< t) [firstDelta + frequency*i | i <- [0..]]
+
+move :: Float -> CowBehavior ()
+move d = do
+    speed <- gets movementSpeed
+    dir <- gets movementDirection
+    pos <- gets position
+    let movementTime = d/speed
+    deltas <- samplingDeltas movementTime
+    let coords = map (\d -> addOffset (speed * d * cos dir, speed * d * sin dir) pos) deltas
+    let finalPos = addOffset (d * cos dir, d * sin dir) pos
+    mapM emitPoint coords
+    increaseTime movementTime
+    setPosition finalPos
+
+turn :: Float -> CowBehavior ()
+turn a = do
+    dir <- gets movementDirection
+    let newDir = dir + (a/180 * pi)
+    setDirection (newDir `mod'` (2*pi))
+
+wait :: Float -> CowBehavior ()
+wait t = do
+    deltas <- samplingDeltas t
+    pos <- gets position
+    mapM (const $ emitPoint pos) deltas
+    increaseTime t
+
+runCow :: Float -> Collar -> [DataPoint]
+runCow f (id, speed, pos, behavior) = zip (cycle [id]) coords
+    where
+        coords = reverse (position finalState : dataPoints finalState)
+        finalState = snd $ runState behavior initialState
+        initialState = CowState
+            { Cdl.Cow.id = id
+            , samplingFrequency = f
+            , movementSpeed = speed
+            , movementDirection = 0
+            , position = pos
+            , time = 0
+            , dataPoints = []
+            }
+
+runCows :: Float -> [Collar] -> [[DataPoint]]
+runCows f cs = transpose $ map (runCow f) $ cs