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Add robot simulator (#393)
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‎config.json

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"prerequisites": [],
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"difficulty": 2
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},
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{
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"slug": "robot-simulator",
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"name": "Robot Simulator",
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"uuid": "575a40bd-2ff9-4623-ae98-c8d9b9f279a8",
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"practices": [],
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"prerequisites": [],
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"difficulty": 2
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},
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{
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"slug": "rna-transcription",
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"name": "RNA Transcription",

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

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

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

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

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

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;;; robot-simulator.el --- robot-simulator Exercise (exercism) -*- lexical-binding: t; -*-
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;;; Commentary:
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;;; Code:
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(defconst directions [north east south west])
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(defconst steps '((north . (0 1))
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(east . (1 0))
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(south . (0 -1))
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(west . (-1 0))))
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(defun create-robot (x y direction)
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(record 'robot x y direction))
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(defun move (robot instructions)
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(let ((state robot))
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(seq-doseq (instruction instructions)
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(cond ((equal ?L instruction)
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(rotate state -1))
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((equal ?R instruction)
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(rotate state 1))
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((equal ?A instruction)
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(advance state))))
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state))
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(defun rotate (robot offset)
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(let* ((old-index (cl-position (aref robot 3) directions))
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(new-index (mod (+ old-index offset) 4)))
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(aset robot 3 (aref directions new-index))))
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(defun advance (robot)
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(let* ((delta (assq (aref robot 3) steps))
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(delta-x (cadr delta))
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(delta-y (caddr delta)))
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(aset robot 1 (+ delta-x (aref robot 1)))
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(aset robot 2 (+ delta-y (aref robot 2)))))
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(provide 'robot-simulator)
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;;; robot-simulator.el ends here

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

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

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

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;;; robot-simulator-test.el --- Tests for robot-simulator (exercism) -*- lexical-binding: t; -*-
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;;; Commentary:
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;;; Code:
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(load-file "robot-simulator.el")
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(declare-function create-robot "robot-simulator.el" (x y direction))
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(declare-function move "robot-simulator.el" (robot instructions))
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(ert-deftest create-robot-at-origin-facing-north ()
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(should (equal #s(robot 0 0 north)
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(create-robot 0 0 'north))))
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(ert-deftest create-robot-at-negative-position-facing-south ()
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(should (equal #s(robot -1 -1 south)
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(create-robot -1 -1 'south))))
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(ert-deftest rotating-clockwise-changes-north-to-east ()
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(should (equal #s(robot 0 0 east)
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(move (create-robot 0 0 'north) "R"))))
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(ert-deftest rotating-clockwise-changes-east-to-south ()
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(should (equal #s(robot 0 0 south)
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(move (create-robot 0 0 'east) "R"))))
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(ert-deftest rotating-clockwise-changes-south-to-west ()
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(should (equal #s(robot 0 0 west)
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(move (create-robot 0 0 'south) "R"))))
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(ert-deftest rotating-clockwise-changes-west-to-north ()
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(should (equal #s(robot 0 0 north)
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(move (create-robot 0 0 'west) "R"))))
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(ert-deftest rotating-counter-clockwise-changes-north-to-west ()
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(should (equal #s(robot 0 0 west)
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(move (create-robot 0 0 'north) "L"))))
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(ert-deftest rotating-counter-clockwise-changes-west-to-south ()
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(should (equal #s(robot 0 0 south)
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(move (create-robot 0 0 'west) "L"))))
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(ert-deftest rotating-counter-clockwise-changes-south-to-east ()
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(should (equal #s(robot 0 0 east)
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(move (create-robot 0 0 'south) "L"))))
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(ert-deftest rotating-counter-clockwise-changes-east-to-north ()
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(should (equal #s(robot 0 0 north)
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(move (create-robot 0 0 'east) "L"))))
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(ert-deftest moving-forward-one-facing-north-increments-y ()
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(should (equal #s(robot 0 1 north)
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(move (create-robot 0 0 'north) "A"))))
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(ert-deftest moving-forward-one-facing-south-decrements-y ()
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(should (equal #s(robot 0 -1 south)
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(move (create-robot 0 0 'south) "A"))))
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(ert-deftest moving-forward-one-facing-east-increments-x ()
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(should (equal #s(robot 1 0 east)
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(move (create-robot 0 0 'east) "A"))))
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(ert-deftest moving-forward-one-facing-west-decrements-x ()
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(should (equal #s(robot -1 0 west)
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(move (create-robot 0 0 'west) "A"))))
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(ert-deftest follow-series-of-instructions-moving-east-and-north-from-README ()
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(should (equal #s(robot 9 4 west)
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(move (create-robot 7 3 'north) "RAALAL"))))
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(ert-deftest follow-series-of-instructions-moving-west-and-north ()
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(should (equal #s(robot -4 1 west)
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(move (create-robot 0 0 'north) "LAAARALA"))))
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(ert-deftest follow-series-of-instructions-moving-west-and-south ()
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(should (equal #s(robot -3 -8 south)
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(move (create-robot 2 -7 'east) "RRAAAAALA"))))
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(ert-deftest follow-series-of-instructions-moving-east-and-north ()
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(should (equal #s(robot 11 5 north)
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(move (create-robot 8 4 'south) "LAAARRRALLLL"))))
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(provide 'robot-simulator-test)
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;;; robot-simulator-test.el ends here

‎exercises/practice/robot-simulator/robot-simulator.el

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;;; robot-simulator.el --- robot-simulator (exercism) -*- lexical-binding: t; -*-
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;;; Commentary:
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;;; Code:
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(defun create-robot (x y direction)
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(error "Delete this S-Expression and write your own implementation"))
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(defun move (robot instructions)
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(error "Delete this S-Expression and write your own implementation"))
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(provide 'robot-simulator)
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;;; robot-simulator.el ends here

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