require.yaml

version: 1
name: Require devices
description: |
  Learn how to require additional devices that would otherwise not be equipped.
objectives:
  - goal:
      - |
        The `build` command automatically equips devices on the newly built robot that it knows will be required.
        For example, if you `build {move}`, some `treads`{=entity} will automatically be equipped on the new robot
        since it needs them to `move`.
      - |
        However, sometimes you need a device but `build` can't tell that you need it.
        In this case, you can use the special `require`{=snippet} command to require a particular device.
        For example, if you run:
        ```
        build {require "boat"; move}
        ```
        Then a `boat`{=entity} will be equipped on the new robot in addition to `treads`{=entity}.
      - |
        Unlike other devices used so far in the tutorial, `boat`{=entity} does not provide any commands,
        but robots that have it equipped will not drown in the `water`{=entity}.
      - |
        Your goal is to pick a flower on the other side of the river and bring it back to your base.
        You win when the base has a `periwinkle`{=entity} flower in its inventory.
      - |
        **TIP:** To see what the `build` command will equip, you can type `requirements <e>`{=snippet}
        where `<e>`{=snippet} is any expression.
    condition: |
      try {
        as base {has "periwinkle"}
      } { pure false }
entities:
  - name: periwinkle
    display:
      attr: flower
      char: '*'
    description:
      - A flower.
    properties: [known, infinite, pickable]
# The player has just done the lambda tutorial, so this neat version is available:
solution: |
  def x5 = \c. c;c;c;c;c end;
  build {
    require "boat";
    turn right; x5 move; f <- grab;
    turn back; x5 move; give base f
  }
robots:
  - name: base
    heavy: true
    dir: north
    display:
      char: Ω
      attr: robot
    devices:
      - logger
      - 3D printer
      - dictionary
    inventory:
      - [10, solar panel]
      - [10, logger]
      - [10, treads]
      - [10, boat]
      - [10, grabber]
      - [10, scanner]
      - [10, compass]
      - [10, lambda]
known: [water, wavy water]
world:
  palette:
    'Ω': [grass, null, base]
    '.': [grass]
    '_': [ice, water]
    '~': [ice, wavy water]
    '*': [grass, periwinkle]
    '+': [stone, wall]
  upperleft: [-1, 3]
  map: |
    ++++++++
    +..~_..+
    +.._~..+
    +Ω.__.*+
    +..~_..+
    +.._~..+
    ++++++++