Add robot-simulator exercise

config.json

@@ -553,6 +553,14 @@
         "prerequisites": [],
         "difficulty": 6
       },
+      {
+        "slug": "robot-simulator",
+        "name": "Robot Simulator",
+        "uuid": "6fc65865-1e9b-48d7-a2c6-6f50bea3b094",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 6
+      },
       {
         "slug": "say",
         "name": "Say",

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": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "robot_simulator.fut"
+    ],
+    "test": [
+      "test.fut"
+    ],
+    "example": [
+      ".meta/example.fut"
+    ]
+  },
+  "blurb": "Write a robot simulator.",
+  "source": "Inspired by an interview question at a famous company."
+}

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

@@ -0,0 +1,45 @@
+type position = (i32, i32)
+
+type direction = #north | #east | #south | #west
+
+type state = (position, direction)
+
+def right (s: state): state =
+  let x = s.0.0
+  let y = s.0.1
+  in
+    match (s.1)
+      case #north -> ((x, y), #east)
+      case #east  -> ((x, y), #south)
+      case #south -> ((x, y), #west)
+      case #west  -> ((x, y), #north)
+
+def left (s: state): state =
+  let x = s.0.0
+  let y = s.0.1
+  in
+    match (s.1)
+      case #north -> ((x, y), #west)
+      case #east  -> ((x, y), #north)
+      case #south -> ((x, y), #east)
+      case #west  -> ((x, y), #south)
+
+def advance (s: state): state =
+  let x = s.0.0
+  let y = s.0.1
+  in
+    match (s.1)
+      case #north -> ((x, y + 1), #north)
+      case #east  -> ((x + 1, y), #east)
+      case #south -> ((x, y - 1), #south)
+      case #west  -> ((x - 1, y), #west)
+
+def move (start: state) (instructions: []u8): state =
+  let s = loop s = start for instruction in instructions do
+    match (instruction)
+      case 'R' -> right s
+      case 'L' -> left s
+      case 'A' -> advance s
+      case _ -> assert false s
+  in
+    s

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.fut

@@ -0,0 +1,7 @@
+type position = (i32, i32)
+
+type direction = #north | #east | #south | #west
+
+type state = (position, direction)
+
+def move (start: state) (instructions: []u8): state = ???

exercises/practice/robot-simulator/test.fut

@@ -0,0 +1,111 @@
+import "robot_simulator"
+
+-- at origin facing north
+-- ==
+-- input  { 0 0 0 "" }
+-- output { [0, 0, 0] }
+
+-- at negative position facing south
+-- ==
+-- input  { -1 -1 2 "" }
+-- output { [-1, -1, 2] }
+
+-- changes north to east
+-- ==
+-- input  { 0 0 0 "R" }
+-- output { [0, 0, 1] }
+
+-- changes east to south
+-- ==
+-- input  { 0 0 1 "R" }
+-- output { [0, 0, 2] }
+
+-- changes south to west
+-- ==
+-- input  { 0 0 2 "R" }
+-- output { [0, 0, 3] }
+
+-- changes west to north
+-- ==
+-- input  { 0 0 3 "R" }
+-- output { [0, 0, 0] }
+
+-- changes north to west
+-- ==
+-- input  { 0 0 0 "L" }
+-- output { [0, 0, 3] }
+
+-- changes west to south
+-- ==
+-- input  { 0 0 3 "L" }
+-- output { [0, 0, 2] }
+
+-- changes south to east
+-- ==
+-- input  { 0 0 2 "L" }
+-- output { [0, 0, 1] }
+
+-- changes east to north
+-- ==
+-- input  { 0 0 1 "L" }
+-- output { [0, 0, 0] }
+
+-- facing north increments Y
+-- ==
+-- input  { 0 0 0 "A" }
+-- output { [0, 1, 0] }
+
+-- facing south decrements Y
+-- ==
+-- input  { 0 0 2 "A" }
+-- output { [0, -1, 2] }
+
+-- facing east increments X
+-- ==
+-- input  { 0 0 1 "A" }
+-- output { [1, 0, 1] }
+
+-- facing west decrements X
+-- ==
+-- input  { 0 0 3 "A" }
+-- output { [-1, 0, 3] }
+
+-- moving east and north from README
+-- ==
+-- input  { 7 3 0 "RAALAL" }
+-- output { [9, 4, 3] }
+
+-- moving west and north
+-- ==
+-- input  { 0 0 0 "LAAARALA" }
+-- output { [-4, 1, 3] }
+
+-- moving west and south
+-- ==
+-- input  { 2 -7 1 "RRAAAAALA" }
+-- output { [-3, -8, 2] }
+
+-- moving east and north
+-- ==
+-- input  { 8 4 2 "LAAARRRALLLL" }
+-- output { [11, 5, 0] }
+
+local def encode_direction (d: direction): i32 =
+    match (d)
+      case #north -> 0
+      case #east -> 1
+      case #south -> 2
+      case #west -> 3
+
+local def decode_direction (i: i32): direction =
+    match (i)
+      case 0 -> #north
+      case 1 -> #east
+      case 2 -> #south
+      case 3 -> #west
+      case _ -> assert false #north
+
+def main (x: i32) (y: i32) (direction: i32) (instructions: []u8): []i32 =
+  let result = move ((x, y), decode_direction direction) instructions
+  in
+    [result.0.0, result.0.1, encode_direction result.1]

generators/exercises/robot_simulator.py

@@ -0,0 +1,47 @@
+MAIN = """\
+local def encode_direction (d: direction): i32 =
+    match (d)
+      case #north -> 0
+      case #east -> 1
+      case #south -> 2
+      case #west -> 3
+
+local def decode_direction (i: i32): direction =
+    match (i)
+      case 0 -> #north
+      case 1 -> #east
+      case 2 -> #south
+      case 3 -> #west
+      case _ -> assert false #north
+
+def main (x: i32) (y: i32) (direction: i32) (instructions: []u8): []i32 =
+  let result = move ((x, y), decode_direction direction) instructions
+  in
+    [result.0.0, result.0.1, encode_direction result.1]
+"""
+
+
+DIRECTIONS = ["north", "east", "south", "west"]
+
+
+def gen_test_case(prop, description, inp, expected, f):
+    in_x = inp["position"]["x"]
+    in_y = inp["position"]["y"]
+    in_d = DIRECTIONS.index(inp["direction"])
+    if "instructions" in inp.keys():
+        instructions = inp["instructions"]
+    else:
+        instructions = ""
+
+    out_x = expected["position"]["x"]
+    out_y = expected["position"]["y"]
+    out_d = DIRECTIONS.index(expected["direction"])
+
+    f.write(f"-- {description}\n")
+    f.write("-- ==\n")
+    f.write(f'-- input  {{ {in_x} {in_y} {in_d} "{instructions}" }}\n')
+    f.write(f"-- output {{ [{out_x}, {out_y}, {out_d}] }}\n\n")
+
+
+def gen_main(f):
+    f.write(MAIN)