Add robot-simulator exercise (#114)

config.json

@@ -167,6 +167,14 @@
         "prerequisites": [],
         "difficulty": 2
       },
+      {
+        "slug": "robot-simulator",
+        "name": "Robot Simulator",
+        "uuid": "609aac37-6b82-4d29-a540-bcad0e80981b",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "scrabble-score",
         "name": "Scrabble Score",

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/Example.roc

@@ -0,0 +1,38 @@
+module [create, move]
+
+Direction : [North, East, South, West]
+Robot : { x : I64, y : I64, direction : Direction }
+
+create : { x ? I64, y ? I64, direction ? Direction } -> Robot
+create = \{ x ? 0, y ? 0, direction ? North } ->
+    { x, y, direction }
+
+move : Robot, Str -> Robot
+move = \robot, instructions ->
+    instructions
+    |> Str.toUtf8
+    |> List.walk robot \{ x, y, direction }, command ->
+        when command is
+            'R' ->
+                when direction is
+                    North -> { x, y, direction: East }
+                    East -> { x, y, direction: South }
+                    South -> { x, y, direction: West }
+                    West -> { x, y, direction: North }
+
+            'L' ->
+                when direction is
+                    North -> { x, y, direction: West }
+                    East -> { x, y, direction: North }
+                    South -> { x, y, direction: East }
+                    West -> { x, y, direction: South }
+
+            'A' ->
+                when direction is
+                    North -> { x, y: y + 1, direction }
+                    East -> { x: x + 1, y, direction }
+                    South -> { x, y: y - 1, direction }
+                    West -> { x: x - 1, y, direction }
+
+            _ -> { x, y, direction } # invalid instructions are ignored
+

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

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

exercises/practice/robot-simulator/.meta/plugins.py

@@ -0,0 +1,13 @@
+def to_robot(robot, with_defaults):
+    x = robot["position"]["x"]
+    y = robot["position"]["y"]
+    direction = robot["direction"]
+    fields = []
+    if x != 0 or not with_defaults:
+        fields.append(f"x : {x}")
+    if y != 0 or not with_defaults:
+        fields.append(f"y : {y}")
+    if direction != "north" or not with_defaults:
+        fields.append(f"direction : {direction.capitalize()}")
+    content = ", ".join(fields)
+    return f"{{{content}}}"

exercises/practice/robot-simulator/.meta/template.j2

@@ -0,0 +1,24 @@
+{%- import "generator_macros.j2" as macros with context -%}
+{{ macros.canonical_ref() }}
+{{ macros.header() }}
+
+import {{ exercise | to_pascal }} exposing [create, move]
+
+{% for supercase in cases %}
+##
+## {{ supercase["description"] }}
+##
+
+{% for case in supercase["cases"] -%}
+# {{ case["description"] }}
+expect
+  {%- if case["input"]["instructions"] %}
+    robot = create {{ plugins.to_robot(case["input"], with_defaults=True) }}
+    result = robot |> move {{ case["input"]["instructions"] | to_roc }}
+  {%- else %}
+    result = create {{ plugins.to_robot(case["input"], with_defaults=True) }}
+  {%- endif %}
+    result == {{ plugins.to_robot(case["expected"], with_defaults=False) }}
+
+{% endfor %}
+{% endfor %}

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/RobotSimulator.roc

@@ -0,0 +1,12 @@
+module [create, move]
+
+Direction : [North, East, South, West]
+Robot : { x : I64, y : I64, direction : Direction }
+
+create : { x ? I64, y ? I64, direction ? Direction } -> Robot
+create = \{ x ? 0, y ? 0, direction ? North } ->
+    crash "Please implement the 'create' function"
+
+move : Robot, Str -> Robot
+move = \robot, instructions ->
+    crash "Please implement the 'move' function"

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

@@ -0,0 +1,138 @@
+# These tests are auto-generated with test data from:
+# https://github.com/exercism/problem-specifications/tree/main/exercises/robot-simulator/canonical-data.json
+# File last updated on 2024-09-23
+app [main] {
+    pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.15.0/SlwdbJ-3GR7uBWQo6zlmYWNYOxnvo8r6YABXD-45UOw.tar.br",
+}
+
+main =
+    Task.ok {}
+
+import RobotSimulator exposing [create, move]
+
+##
+## Create robot
+##
+
+# at origin facing north
+expect
+    result = create {}
+    result == { x: 0, y: 0, direction: North }
+
+# at negative position facing south
+expect
+    result = create { x: -1, y: -1, direction: South }
+    result == { x: -1, y: -1, direction: South }
+
+##
+## Rotating clockwise
+##
+
+# changes north to east
+expect
+    robot = create {}
+    result = robot |> move "R"
+    result == { x: 0, y: 0, direction: East }
+
+# changes east to south
+expect
+    robot = create { direction: East }
+    result = robot |> move "R"
+    result == { x: 0, y: 0, direction: South }
+
+# changes south to west
+expect
+    robot = create { direction: South }
+    result = robot |> move "R"
+    result == { x: 0, y: 0, direction: West }
+
+# changes west to north
+expect
+    robot = create { direction: West }
+    result = robot |> move "R"
+    result == { x: 0, y: 0, direction: North }
+
+##
+## Rotating counter-clockwise
+##
+
+# changes north to west
+expect
+    robot = create {}
+    result = robot |> move "L"
+    result == { x: 0, y: 0, direction: West }
+
+# changes west to south
+expect
+    robot = create { direction: West }
+    result = robot |> move "L"
+    result == { x: 0, y: 0, direction: South }
+
+# changes south to east
+expect
+    robot = create { direction: South }
+    result = robot |> move "L"
+    result == { x: 0, y: 0, direction: East }
+
+# changes east to north
+expect
+    robot = create { direction: East }
+    result = robot |> move "L"
+    result == { x: 0, y: 0, direction: North }
+
+##
+## Moving forward one
+##
+
+# facing north increments Y
+expect
+    robot = create {}
+    result = robot |> move "A"
+    result == { x: 0, y: 1, direction: North }
+
+# facing south decrements Y
+expect
+    robot = create { direction: South }
+    result = robot |> move "A"
+    result == { x: 0, y: -1, direction: South }
+
+# facing east increments X
+expect
+    robot = create { direction: East }
+    result = robot |> move "A"
+    result == { x: 1, y: 0, direction: East }
+
+# facing west decrements X
+expect
+    robot = create { direction: West }
+    result = robot |> move "A"
+    result == { x: -1, y: 0, direction: West }
+
+##
+## Follow series of instructions
+##
+
+# moving east and north from README
+expect
+    robot = create { x: 7, y: 3 }
+    result = robot |> move "RAALAL"
+    result == { x: 9, y: 4, direction: West }
+
+# moving west and north
+expect
+    robot = create {}
+    result = robot |> move "LAAARALA"
+    result == { x: -4, y: 1, direction: West }
+
+# moving west and south
+expect
+    robot = create { x: 2, y: -7, direction: East }
+    result = robot |> move "RRAAAAALA"
+    result == { x: -3, y: -8, direction: South }
+
+# moving east and north
+expect
+    robot = create { x: 8, y: 4, direction: South }
+    result = robot |> move "LAAARRRALLLL"
+    result == { x: 11, y: 5, direction: North }
+