Add robot-simulator (#176)

config.json

@@ -411,6 +411,16 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "robot-simulator",
+        "name": "Robot Simulator",
+        "uuid": "e81a517a-16be-4760-980a-21ee549c24ea",
+        "practices": [
+          "strings"
+        ],
+        "prerequisites": [],
+        "difficulty": 4
+      },
       {
         "slug": "roman-numerals",
         "name": "Roman Numerals",

exercises/practice/robot-simulator/.docs/instructions.md

@@ -0,0 +1,25 @@
+# Instructions
+
+Write a robot simulator.
+
+A robot factory's test facility needs a program to verify robot movements.
+
+The robots have three possible movements:
+
+- turn right
+- turn left
+- advance
+
+Robots are placed on a hypothetical infinite grid, facing a particular direction (north, east, south, or west) at a set of {x,y} coordinates,
+e.g., {3,8}, with coordinates increasing to the north and east.
+
+The robot then receives a number of instructions, at which point the testing facility verifies the robot's new position, and in which direction it is pointing.
+
+- The letter-string "RAALAL" means:
+  - Turn right
+  - Advance twice
+  - Turn left
+  - Advance once
+  - Turn left yet again
+- Say a robot starts at {7, 3} facing north.
+  Then running this stream of instructions should leave it at {9, 4} facing west.

exercises/practice/robot-simulator/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "robot-simulator.arr"
+    ],
+    "test": [
+      "robot-simulator-test.arr"
+    ],
+    "example": [
+      ".meta/example.arr"
+    ]
+  },
+  "blurb": "Write a robot simulator.",
+  "source": "Inspired by an interview question at a famous company."
+}

exercises/practice/robot-simulator/.meta/example.arr

@@ -0,0 +1,51 @@
+use context essentials2020
+
+provide-types *
+
+include string-dict
+import lists as L
+
+data Axis: axis(label, left, right) end
+
+cardinal_axes = [string-dict:
+  'north', axis('north', 'west', 'east'),
+  'south', axis('south', 'east', 'west'),
+  'east', axis('east', 'north','south'),
+  'west', axis('west','south', 'north'),
+]
+
+data Robot:
+  | robot(x :: NumInteger, y :: NumInteger, direction :: String) with:
+    method move(self, directions :: String) -> Robot:
+      L.foldl(
+        lam(acc, elt):
+          direction = 
+            ask:
+              | elt == 'L' then:
+                cardinal_axes.get-value(acc.direction).left
+              | elt == 'R' then:
+                cardinal_axes.get-value(acc.direction).right
+              | otherwise:
+                acc.direction
+            end
+          {x; y} =
+            if elt == 'A':
+              ask:
+                | direction == 'north' then:
+                  {acc.x; acc.y + 1}
+                | direction == 'south' then:
+                  {acc.x; acc.y - 1}
+                | direction == 'east' then:
+                  {acc.x + 1; acc.y}
+                | direction == 'west' then:
+                  {acc.x - 1; acc.y}
+              end
+            else:
+              {acc.x; acc.y}
+            end
+          robot(x, y, direction)
+        end,
+        self,
+        string-explode(directions))
+  end
+end

exercises/practice/robot-simulator/.meta/tests.toml

@@ -0,0 +1,64 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[c557c16d-26c1-4e06-827c-f6602cd0785c]
+description = "Create robot -> at origin facing north"
+
+[bf0dffce-f11c-4cdb-8a5e-2c89d8a5a67d]
+description = "Create robot -> at negative position facing south"
+
+[8cbd0086-6392-4680-b9b9-73cf491e67e5]
+description = "Rotating clockwise -> changes north to east"
+
+[8abc87fc-eab2-4276-93b7-9c009e866ba1]
+description = "Rotating clockwise -> changes east to south"
+
+[3cfe1b85-bbf2-4bae-b54d-d73e7e93617a]
+description = "Rotating clockwise -> changes south to west"
+
+[5ea9fb99-3f2c-47bd-86f7-46b7d8c3c716]
+description = "Rotating clockwise -> changes west to north"
+
+[fa0c40f5-6ba3-443d-a4b3-58cbd6cb8d63]
+description = "Rotating counter-clockwise -> changes north to west"
+
+[da33d734-831f-445c-9907-d66d7d2a92e2]
+description = "Rotating counter-clockwise -> changes west to south"
+
+[bd1ca4b9-4548-45f4-b32e-900fc7c19389]
+description = "Rotating counter-clockwise -> changes south to east"
+
+[2de27b67-a25c-4b59-9883-bc03b1b55bba]
+description = "Rotating counter-clockwise -> changes east to north"
+
+[f0dc2388-cddc-4f83-9bed-bcf46b8fc7b8]
+description = "Moving forward one -> facing north increments Y"
+
+[2786cf80-5bbf-44b0-9503-a89a9c5789da]
+description = "Moving forward one -> facing south decrements Y"
+
+[84bf3c8c-241f-434d-883d-69817dbd6a48]
+description = "Moving forward one -> facing east increments X"
+
+[bb69c4a7-3bbf-4f64-b415-666fa72d7b04]
+description = "Moving forward one -> facing west decrements X"
+
+[e34ac672-4ed4-4be3-a0b8-d9af259cbaa1]
+description = "Follow series of instructions -> moving east and north from README"
+
+[f30e4955-4b47-4aa3-8b39-ae98cfbd515b]
+description = "Follow series of instructions -> moving west and north"
+
+[3e466bf6-20ab-4d79-8b51-264165182fca]
+description = "Follow series of instructions -> moving west and south"
+
+[41f0bb96-c617-4e6b-acff-a4b279d44514]
+description = "Follow series of instructions -> moving east and north"

exercises/practice/robot-simulator/robot-simulator-test.arr

@@ -0,0 +1,182 @@
+use context essentials2020
+
+include file("robot-simulator.arr")
+
+#|
+  When working offline, all tests except the first one are skipped by default.
+  Once you get the first test running, unskip the next one until all tests pass locally.
+  Check the block comment below for further details.
+|#
+
+fun create-robot-at-origin-facing-north():
+  check "Create robot at origin facing north":
+    r = robot(0, 0, 'north')
+    expected = robot(0, 0, 'north')
+    r is expected
+  end
+end
+
+fun create-robot-at-negative-position-facing-south():
+  check "Create robot at negative position facing south":
+    r = robot(-1, -1, 'south')
+    expected = robot(-1, -1, 'south')
+    r is expected
+  end
+end
+
+fun rotating-clockwise-changes-north-to-east():
+  check "Rotating clockwise changes north to east":
+    r = robot(0, 0, 'north')
+    expected = robot(0, 0, 'east')
+    r.move('R') is expected
+  end
+end
+
+fun rotating-clockwise-changes-east-to-south():
+  check "Rotating clockwise changes east to south":
+    r = robot(0, 0, 'east')
+    expected = robot(0, 0, 'south')
+    r.move('R') is expected
+  end
+end
+
+fun rotating-clockwise-changes-south-to-west():
+  check "Rotating clockwise changes south to west":
+    r = robot(0, 0, 'south')
+    expected = robot(0, 0, 'west')
+    r.move('R') is expected
+  end
+end
+
+fun rotating-clockwise-changes-west-to-north():
+  check "Rotating clockwise changes west to north":
+    r = robot(0, 0, 'west')
+    expected = robot(0, 0, 'north')
+    r.move('R') is expected
+  end
+end
+
+fun rotating-counter-clockwise-changes-north-to-west():
+  check "Rotating counter-clockwise changes north to west":
+    r = robot(0, 0, 'north')
+    expected = robot(0, 0, 'west')
+    r.move('L') is expected
+  end
+end
+
+fun rotating-counter-clockwise-changes-west-to-south():
+  check "Rotating counter-clockwise changes west to south":
+    r = robot(0, 0, 'west')
+    expected = robot(0, 0, 'south')
+    r.move('L') is expected
+  end
+end
+
+fun rotating-counter-clockwise-changes-south-to-east():
+  check "Rotating counter-clockwise changes south to east":
+    r = robot(0, 0, 'south')
+    expected = robot(0, 0, 'east')
+    r.move('L') is expected
+  end
+end
+
+fun rotating-counter-clockwise-changes-east-to-north():
+  check "Rotating counter-clockwise changes east to north":
+    r = robot(0, 0, 'east')
+    expected = robot(0, 0, 'north')
+    r.move('L') is expected
+  end
+end
+
+fun moving-forward-one-facing-north-increments-Y():
+  check "Moving forward one facing north increments Y":
+    r = robot(0, 0, 'north')
+    expected = robot(0, 1, 'north')
+    r.move('A') is expected
+  end
+end
+
+fun moving-forward-one-facing-south-decrements-Y():
+  check "Moving forward one facing south decrements Y":
+    r = robot(0, 0, 'south')
+    expected = robot(0, -1, 'south')
+    r.move('A') is expected
+  end
+end
+
+fun moving-forward-one-facing-east-increments-X():
+  check "Moving forward one facing east increments X":
+    r = robot(0, 0, 'east')
+    expected = robot(1, 0, 'east')
+    r.move('A') is expected
+  end
+end
+
+fun moving-forward-one-facing-west-decrements-X():
+  check "Moving forward one facing west decrements X":
+    r = robot(0, 0, 'west')
+    expected = robot(-1, 0, 'west')
+    r.move('A') is expected
+  end
+end
+
+fun follow-series-of-directions-moving-east-and-north-from-readme():
+  check "Follow series of directions moving east and north from README":
+    r = robot(7, 3, 'north')
+    expected = robot(9, 4, 'west')
+    r.move('RAALAL') is expected
+  end
+end
+
+fun follow-series-of-directions-moving-west-and-north():
+  check "Follow series of directions moving west and north":
+    r = robot(0, 0, 'north')
+    expected = robot(-4, 1, 'west')
+    r.move('LAAARALA') is expected
+  end
+end
+
+fun follow-series-of-directions-moving-west-and-south():
+  check "Follow series of directions moving west and south":
+    r = robot(2, -7, 'east')
+    expected = robot(-3, -8, 'south')
+    r.move('RRAAAAALA') is expected
+  end
+end
+
+fun follow-series-of-directions-moving-east-and-north():
+  check "Follow series of directions moving east and north":
+    r = robot(8, 4, 'south')
+    expected = robot(11, 5, 'north')
+    r.move('LAAARRRALLLL') is expected
+  end
+end
+
+#|
+  Code to run each test. Each line corresponds to a test above and whether it should be run.
+  To mark a test to be run, replace `false` with `true` on that same line after the comma.
+  test(test-a, true) will be run. test(test-a, false) will be skipped.
+|#
+
+data TestRun: test(run, active) end
+
+[list: 
+  test(create-robot-at-origin-facing-north, true),
+  test(create-robot-at-negative-position-facing-south, false),
+  test(rotating-clockwise-changes-north-to-east, false),
+  test(rotating-clockwise-changes-east-to-south, false),
+  test(rotating-clockwise-changes-south-to-west, false),
+  test(rotating-clockwise-changes-west-to-north, false),
+  test(rotating-counter-clockwise-changes-north-to-west, false),
+  test(rotating-counter-clockwise-changes-west-to-south, false),
+  test(rotating-counter-clockwise-changes-south-to-east, false),
+  test(rotating-counter-clockwise-changes-east-to-north, false),
+  test(moving-forward-one-facing-north-increments-Y, false),
+  test(moving-forward-one-facing-south-decrements-Y, false),
+  test(moving-forward-one-facing-east-increments-X, false),
+  test(moving-forward-one-facing-west-decrements-X, false),
+  test(follow-series-of-directions-moving-east-and-north-from-readme, false),
+  test(follow-series-of-directions-moving-west-and-north, false),
+  test(follow-series-of-directions-moving-west-and-south, false),
+  test(follow-series-of-directions-moving-east-and-north, false)
+].each(lam(t): when t.active: t.run() end end)

exercises/practice/robot-simulator/robot-simulator.arr

@@ -0,0 +1,11 @@
+use context essentials2020 # Don't delete this line when using Pyret on Exercism
+
+provide-types *
+
+data Robot:
+  | robot()
+    with:
+    method move(self, directions :: String) -> Robot:
+      ...
+    end
+end