version: 1
name: Require inventory
description: |
  Learn how to require inventory when building robots.
objectives:
  - goal:
      - In the previous tutorial challenge, you learned how to use
        `require` to require specific devices to be equipped.
        Sometimes, instead of requiring equipped devices, you require
        supplies in your inventory.  In this case, you can write
        `require <int> <name>` to require a certain number of copies of
        a certain entity to be placed in your inventory.
      - For example, `build {require 10 "flower"; move; move}` would
        build a robot with 10 flowers in its inventory.
      - Your goal in this challenge is to cover the entire 4x4 gray area
        with rocks!
      - |
        Remember that you can define commands to simplify your task, for example:
      - |
        `def PR = move; place "rock" end`
    condition: |
      def repeat = \n. \c. if (n == 0) {} {c ; repeat (n-1) c} end;
      def ifC = \test. \then. \else. b <- test; if b then else end;
      try {
        teleport self (0,0); turn south;
        repeat 4 (
          move; turn east;
          repeat 4 (
            move;
            ifC (ishere "rock") {} {create "tree"};
          );
          turn back; move; move; move; move; turn left
        );
        ifC (has "tree") {return false} {return true}
      } { return false }
solution: |
  def x4 = \c. c;c;c;c end;
  def mp = move; place "rock" end;
  def rr = turn right; move; turn right; x4 mp; turn back; x4 move end;
  build {
    require 16 "rock";
    x4 rr
  };
robots:
  - name: base
    heavy: true
    dir: [0,1]
    display:
      char: Ω
      attr: robot
    devices:
      - logger
      - 3D printer
      - dictionary
    inventory:
      - [16, compass]
      - [16, solar panel]
      - [16, logger]
      - [16, treads]
      - [16, grabber]
      - [16, scanner]
      - [16, lambda]
      - [100, rock]
world:
  default: [blank]
  palette:
    'Ω': [grass, null, base]
    '.': [grass]
    '_': [stone]
    '┌': [stone, upper left corner]
    '┐': [stone, upper right corner]
    '└': [stone, lower left corner]
    '┘': [stone, lower right corner]
    '─': [stone, horizontal wall]
    '│': [stone, vertical wall]
  upperleft: [-1, 1]
  map: |
    ┌─────┐
    │Ω....│
    │.____│
    │.____│
    │.____│
    │.____│
    └─────┘