'Be' command for unprivileged 'As'

editors/emacs/swarm-mode.el

@@ -112,6 +112,7 @@
                "installkeyhandler"
                "teleport"
                "as"
+               "be"
                "robotnamed"
                "robotnumbered"
                "knows"

editors/vim/swarm.vim

@@ -1,6 +1,6 @@
 syn keyword Keyword def end let in require
 syn keyword Builtins self parent base if inl inr case fst snd force undefined fail not format chars split charat tochar key
-syn keyword Command noop wait selfdestruct move backup push stride turn grab harvest ignite place give equip unequip make has equipped count drill use build salvage reprogram say listen log view appear create halt time scout whereami waypoint detect resonate density sniff chirp watch surveil heading blocked scan upload ishere isempty meet meetall whoami setname random run return try swap atomic instant installkeyhandler teleport as robotnamed robotnumbered knows
+syn keyword Command noop wait selfdestruct move backup push stride turn grab harvest ignite place give equip unequip make has equipped count drill use build salvage reprogram say listen log view appear create halt time scout whereami waypoint detect resonate density sniff chirp watch surveil heading blocked scan upload ishere isempty meet meetall whoami setname random run return try swap atomic instant installkeyhandler teleport as be robotnamed robotnumbered knows
 syn keyword Direction east north west south down forward left back right
 syn keyword Type int text dir bool cmd void unit actor
 

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|key|noop|wait|selfdestruct|move|backup|push|stride|turn|grab|harvest|ignite|place|give|equip|unequip|make|has|equipped|count|drill|use|build|salvage|reprogram|say|listen|log|view|appear|create|halt|time|scout|whereami|waypoint|detect|resonate|density|sniff|chirp|watch|surveil|heading|blocked|scan|upload|ishere|isempty|meet|meetall|whoami|setname|random|run|return|try|swap|atomic|instant|installkeyhandler|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|key|noop|wait|selfdestruct|move|backup|push|stride|turn|grab|harvest|ignite|place|give|equip|unequip|make|has|equipped|count|drill|use|build|salvage|reprogram|say|listen|log|view|appear|create|halt|time|scout|whereami|waypoint|detect|resonate|density|sniff|chirp|watch|surveil|heading|blocked|scan|upload|ishere|isempty|meet|meetall|whoami|setname|random|run|return|try|swap|atomic|instant|installkeyhandler|teleport|as|be|robotnamed|robotnumbered|knows)\\b"
 				}
 			]
 			},

src/Swarm/Game/Step.hs

@@ -1479,26 +1479,8 @@ execConst c vs s k = do
       _ -> badConst
     Atomic -> goAtomic
     Instant -> goAtomic
-    As -> case vs of
-      [VRobot rid, prog] -> do
-        -- Get the named robot and current game state
-        r <- robotWithID rid >>= (`isJustOrFail` ["There is no actor with ID", from (show rid)])
-        g <- get @GameState
-
-        -- Execute the given program *hypothetically*: i.e. in a fresh
-        -- CESK machine, using *copies* of the current store, robot
-        -- and game state.  We discard the state afterwards so any
-        -- modifications made by prog do not persist.  Note we also
-        -- set the copied robot to be a "system" robot so it is
-        -- capable of executing any commands; the As command
-        -- already requires "God" capability.
-        v <-
-          evalState @Robot (r & systemRobot .~ True) . evalState @GameState g $
-            runCESK (Out prog s [FApp (VCApp Force []), FExec])
-
-        -- Return the value returned by the hypothetical command.
-        return $ Out v s k
-      _ -> badConst
+    As -> impersonateCommand True
+    Be -> impersonateCommand False
     RobotNamed -> case vs of
       [VText rname] -> do
         r <- robotWithName rname >>= (`isJustOrFail` ["There is no robot named", rname])
@@ -2093,6 +2075,25 @@ execConst c vs s k = do
       DRelative (DPlanar DBack) -> "behind"
       _ -> directionSyntax d <> " of"
 
+  impersonateCommand forceSystemRobot = case vs of
+    [VRobot rid, prog] -> do
+      -- Get the named robot and current game state
+      r <- robotWithID rid >>= (`isJustOrFail` ["There is no actor with ID", from (show rid)])
+      g <- get @GameState
+
+      let modifiedRobot = applyWhen forceSystemRobot (\x -> x & systemRobot .~ True) r
+      -- Execute the given program *hypothetically*: i.e. in a fresh
+      -- CESK machine, using *copies* of the current store, robot
+      -- and game state.  We discard the state afterwards so any
+      -- modifications made by prog do not persist.
+      v <-
+        evalState @Robot modifiedRobot . evalState @GameState g $
+          runCESK (Out prog s [FApp (VCApp Force []), FExec])
+
+      -- Return the value returned by the hypothetical command.
+      return $ Out v s k
+    _ -> badConst
+
   goAtomic :: HasRobotStepState sig m => m CESK
   goAtomic = case vs of
     -- To execute an atomic block, set the runningAtomic flag,

src/Swarm/Language/Capability.hs

@@ -274,6 +274,7 @@ constCaps = \case
   -- ----------------------------------------------------------------
   -- Some God-like abilities.
   As -> Just CGod
+  Be -> Just CGod
   RobotNamed -> Just CGod
   RobotNumbered -> Just CGod
   Create -> Just CGod

src/Swarm/Language/Syntax.hs

@@ -364,8 +364,10 @@ data Const
 
     -- | Teleport a robot to the given position.
     Teleport
-  | -- | Run a command as if you were another robot.
+  | -- | Run a command as if you were another robot, and with "system robot" privileges.
     As
+  | -- | Run a command as if you were another robot.
+    Be
   | -- | Find an actor by name.
     RobotNamed
   | -- | Find an actor by number.
@@ -762,7 +764,8 @@ constInfo c = case c of
       , "The second argument is a function to handle keyboard inputs."
       ]
   Teleport -> command 2 short "Teleport a robot to the given location."
-  As -> command 2 Intangible "Hypothetically run a command as if you were another robot."
+  As -> command 2 Intangible "Hypothetically run a command as if you were another robot, with system privileges."
+  Be -> command 2 Intangible "Hypothetically run a command as if you were another robot."
   RobotNamed -> command 1 Intangible "Find an actor by name."
   RobotNumbered -> command 1 Intangible "Find an actor by number."
   Knows -> command 1 Intangible "Check if the robot knows about an entity."

src/Swarm/Language/Typecheck.hs

@@ -834,6 +834,7 @@ inferConst c = case c of
   InstallKeyHandler -> [tyQ| text -> (key -> cmd unit) -> cmd unit |]
   Teleport -> [tyQ| actor -> (int * int) -> cmd unit |]
   As -> [tyQ| actor -> {cmd a} -> cmd a |]
+  Be -> [tyQ| actor -> {cmd a} -> cmd a |]
   RobotNamed -> [tyQ| text -> cmd actor |]
   RobotNumbered -> [tyQ| int -> cmd actor |]
   Knows -> [tyQ| text -> cmd bool |]