Add GPS receiver device to provide senseloc capability (#956)

Add a new `GPS receiver` device which enables the `senseloc` capability (and hence the `whereami` command).  Towards #26 .

- My immediate motivation is that I want to be able to define `excursion : cmd unit -> cmd unit` which executes the given command and then returns to the same location and orientation as before.  Being able to use the `whereami` command is one of the last missing pieces of machinery necessary to be able to do this in classic mode (the other is a `heading` command, see #955).
- The proposed recipe for `GPS receiver` is `antenna + circuit + clock + compass`, which is a somewhat difficult recipe (`antenna` requires `silver` which requires a `deep mine`; a `clock` requires `quartz` + a bunch of `iron gears`, etc.).  One might wonder whether we should make the recipe easier since finding out where you are seems like a kind of fundamental operation.  However, consider that in order to even be able to make use of the result of `whereami` you need at least (1) an `ADT calculator` to deal with the pair (which transitively requires `typewriter` -> `circuit` -> `silicon` -> `quartz`) (2) probably things like `comparator` and `calculator` to do anything useful with the coordinates.  By the time you have those things you can definitely already build `circuit` + `clock` + `compass`, and you're probably not that far away from getting some `silver` for an `antenna`.  Also, in practice it's an interesting/fun constraint to build up machinery that has to work entirely based on *relative* position without being able to find out your absolute coordinates.
- For some reason this is causing `Testing/508-capability-subset` to fail.  I think perhaps it is due to #397 ?  I will investigate. *EDIT*: unfortunately, that wasn't it!

data/entities.yaml

@@ -1146,3 +1146,15 @@
     `b1 <- f b0 x; b2 <- f b1 y; f b2 z`.
   properties: [portable]
   capabilities: [meet]
+
+- name: GPS receiver
+  display:
+    attr: device
+    char: 'G'
+  description:
+  - |
+    A GPS receiver triangulates your current (x,y) coordinates from
+    some convenient satellite signals,
+    enabling the command `whereami : cmd (int * int)`.
+  properties: [portable]
+  capabilities: [senseloc]

data/recipes.yaml

@@ -508,6 +508,20 @@
   out:
   - [1, bitcoin]
 
+- in:
+  - [2, silver]
+  - [2, copper wire]
+  out:
+  - [1, antenna]
+
+- in:
+  - [1, antenna]
+  - [1, clock]
+  - [1, circuit]
+  - [1, compass]
+  out:
+  - [1, GPS receiver]
+
 ## MAGIC
 
 - in:
@@ -670,12 +684,6 @@
   out:
   - [1, mirror]
 
-- in:
-  - [2, silver]
-  - [2, copper wire]
-  out:
-  - [1, antenna]
-
 #########################################
 ##                 LAMBDA              ##
 #########################################

data/scenarios/Testing/00-ORDER.txt

@@ -19,3 +19,4 @@
 955-heading.yaml
 397-wrong-missing.yaml
 961-custom-capabilities.yaml
+956-GPS.yaml

data/scenarios/Testing/956-GPS.yaml

@@ -0,0 +1,66 @@
+version: 1
+name: Test GPS receiver device
+description: |
+  Test the `whereami` command and GPS receiver device.
+  https://github.com/swarm-game/swarm/issues/956
+objectives:
+  - condition: |
+      loc <- as base {whereami};
+      return $ loc == (0,0)
+    goal:
+      - |
+        The goal is to move back to the origin after being
+        unceremoniously teleported to a random location.  The only way
+        to do this is to use a GPS receiver device to learn the
+        current location and use the result to decide how to move.
+solution: |
+  def x = \n. \c. if (n == 0) {} {c ; x (n-1) c} end;
+  def abs = \n. if (n<0) {-n} {n} end;
+  wait 2;
+  loc <- whereami;
+  turn (if (fst loc < 0) {east} {west}); x (abs (fst loc)) move;
+  turn (if (snd loc < 0) {north} {south}); x (abs (snd loc)) move;
+robots:
+  - name: base
+    dir: [0,1]
+    loc: [-5,5]
+    devices:
+      - clock
+      - dictionary
+      - GPS receiver
+      - treads
+      - compass
+      - ADT calculator
+      - strange loop
+      - comparator
+      - calculator
+      - branch predictor
+      - logger
+  - name: teleporter
+    dir: [0,1]
+    loc: [0,0]
+    system: true
+    display:
+      invisible: true
+    program: |
+      x <- random 11;
+      y <- random 11;
+      teleport base (x-5, y-5)
+world:
+  default: [blank]
+  palette:
+    '.': [grass]
+  upperleft: [-5, 5]
+  map: |
+    ...........
+    ...........
+    ...........
+    ...........
+    ...........
+    ...........
+    ...........
+    ...........
+    ...........
+    ...........
+    ...........
+

src/Swarm/Language/Capability.hs

@@ -211,6 +211,7 @@ constCaps = \case
   Atomic -> Just CAtomic
   Time -> Just CTime
   Wait -> Just CTime
+  Whereami -> Just CSenseloc
   Heading -> Just COrient
   -- ----------------------------------------------------------------
   -- Text operations
@@ -257,7 +258,6 @@ constCaps = \case
   -- which conveys their capability. TODO: #26
   Teleport -> Just CTeleport -- Some space-time machine like Tardis?
   Appear -> Just CAppear -- paint?
-  Whereami -> Just CSenseloc -- GPS?
   Random -> Just CRandom -- randomness device (with bitcoins)?
   -- ----------------------------------------------------------------
   -- Some more constants which *ought* to have their own capability but

test/integration/Main.hs

@@ -219,17 +219,18 @@ testScenarioSolution _ci _em =
         , testSolution Default "Testing/710-multi-robot"
         , testSolution Default "Testing/920-meet"
         , testSolution Default "Testing/955-heading"
-        , testSolution' Default "Testing/397-wrong-missing" AllowBadErrors $ \g -> do
+        , testSolution' Default "Testing/397-wrong-missing" CheckForBadErrors $ \g -> do
             let msgs =
                   (g ^. messageQueue . to seqToTexts)
                     <> (g ^.. robotMap . traverse . robotLog . to seqToTexts . traverse)
 
             assertBool "Should be some messages" (not (null msgs))
             assertBool "Error messages should not mention treads" $
               not (any ("treads" `T.isInfixOf`) msgs)
-            assertBool "Error message should mention no device provides senseloc" $
-              any ("senseloc" `T.isInfixOf`) msgs
+            assertBool "Error message should mention GPS receiver" $
+              any ("GPS receiver" `T.isInfixOf`) msgs
         , testSolution Default "Testing/961-custom-capabilities"
+        , testSolution Default "Testing/956-GPS"
         ]
     ]
  where