Sniff command

towards #1171

editors/emacs/swarm-mode.el

@@ -77,6 +77,7 @@
                "time"
                "whereami"
                "detect"
+               "sniff"
                "heading"
                "blocked"
                "scan"

editors/vscode/syntaxes/swarm.tmLanguage.json

@@ -58,7 +58,7 @@
 				},
 				{
 				"name": "keyword.other",
-				"match": "\\b(?i)(self|parent|base|if|inl|inr|case|fst|snd|force|undefined|fail|not|format|chars|split|charat|tochar|noop|wait|selfdestruct|move|turn|grab|harvest|place|give|equip|unequip|make|has|equipped|count|drill|build|salvage|reprogram|say|listen|log|view|appear|create|time|whereami|detect|heading|blocked|scan|upload|ishere|isempty|meet|meetall|whoami|setname|random|run|return|try|swap|atomic|teleport|as|robotnamed|robotnumbered|knows)\\b"
+				"match": "\\b(?i)(self|parent|base|if|inl|inr|case|fst|snd|force|undefined|fail|not|format|chars|split|charat|tochar|noop|wait|selfdestruct|move|turn|grab|harvest|place|give|equip|unequip|make|has|equipped|count|drill|build|salvage|reprogram|say|listen|log|view|appear|create|time|whereami|detect|sniff|heading|blocked|scan|upload|ishere|isempty|meet|meetall|whoami|setname|random|run|return|try|swap|atomic|teleport|as|robotnamed|robotnumbered|knows)\\b"
 				}
 			]
 			},

src/Swarm/Game/Step.hs

@@ -57,7 +57,7 @@ import Data.Text (Text)
 import Data.Text qualified as T
 import Data.Time (getZonedTime)
 import Data.Tuple (swap)
-import Linear (V2 (..), zero)
+import Linear (V2 (..), zero, perp)
 import Swarm.Game.Achievement.Attainment
 import Swarm.Game.Achievement.Definitions
 import Swarm.Game.CESK
@@ -90,6 +90,10 @@ import System.Clock qualified
 import System.Random (UniformRange, uniformR)
 import Witch (From (from), into)
 import Prelude hiding (lookup)
+import Data.Int (Int32)
+
+maxSniffRange :: Int32
+maxSniffRange = 250
 
 -- | The main function to do one game step.
 --
@@ -1206,6 +1210,16 @@ execConst c vs s k = do
         firstOne <- findM (fmap (maybe False $ isEntityNamed name) . entityAt . (loc .+^)) sortedLocs
         return $ Out (asValue firstOne) s k
       _ -> badConst
+    Sniff -> case vs of
+      [VText name] -> do
+        loc <- use robotLocation
+        -- Grow a list of locations in a diamond shape outward, such that the nearest cells
+        -- are searched first by construction.
+        let genDiamondSide diameter = concat [map (diameter,)$ take 4 $ iterate perp $ V2 x (diameter - x) | x <- [0..diameter]]
+        let sortedLocs = (0, zero) : concatMap genDiamondSide [1..maxSniffRange]
+        firstOne <- findM (fmap (maybe False $ isEntityNamed name) . entityAt . (loc .+^) . snd) sortedLocs
+        return $ Out (asValue $ maybe (-1) fst firstOne) s k
+      _ -> badConst
     Heading -> do
       mh <- use robotOrientation
       -- In general, (1) entities might not have an orientation, and

src/Swarm/Language/Capability.hs

@@ -72,6 +72,8 @@ data Capability
     CSensehere
   | -- | Execute the 'Detect' command
     CDetectloc
+  | -- | Execute the 'Sniff' command
+    CDetectdistance
   | -- | Execute the 'Scan' command
     CScan
   | -- | Execute the 'Random' command
@@ -216,6 +218,7 @@ constCaps = \case
   Wait -> Just CTime
   Whereami -> Just CSenseloc
   Detect -> Just CDetectloc
+  Sniff -> Just CDetectdistance
   Heading -> Just COrient
   -- ----------------------------------------------------------------
   -- Text operations

src/Swarm/Language/Syntax.hs

@@ -234,6 +234,9 @@ data Const
   | -- | Locate the closest instance of a given entity within the rectangle
     -- specified by opposite corners, relative to the current location.
     Detect
+  | -- | Get the distance to the closest instance of the specified entity.
+    -- Returns (-1) if none found.
+    Sniff
   | -- | Get the current heading.
     Heading
   | -- | See if we can move forward or not.
@@ -584,6 +587,12 @@ constInfo c = case c of
   Detect ->
     command 2 Intangible . doc "Detect an entity within a rectangle." $
       ["Locate the closest instance of a given entity within the rectangle specified by opposite corners, relative to the current location."]
+  Sniff ->
+    command 1 short . doc "Determine distance to entity." $
+      [ "Measures concentration of airborne particles to infer distance to a certain kind of entity."
+      , "If none is detected, returns (-1)."
+      , "Has a max range of 250 units."
+      ]
   Heading -> command 0 Intangible "Get the current heading."
   Blocked -> command 0 Intangible "See if the robot can move forward."
   Scan ->

src/Swarm/Language/Typecheck.hs

@@ -560,6 +560,7 @@ inferConst c = case c of
   Time -> [tyQ| cmd int |]
   Whereami -> [tyQ| cmd (int * int) |]
   Detect -> [tyQ| text -> ((int * int) * (int * int)) -> cmd (unit + (int * int)) |]
+  Sniff -> [tyQ| text -> cmd int |]
   Heading -> [tyQ| cmd dir |]
   Blocked -> [tyQ| cmd bool |]
   Scan -> [tyQ| dir -> cmd (unit + text) |]