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Lecture 22 Scheme Data Abstraction

  1. Questions
  2. Data Abstraction
    1. Don’t need to know how things are implemented
    2. Only need to know what its behavior is
    3. Group - A scheme data abstraction
      1. (group first-val second-val)
      2. constructs a new group from 2 arguments
      3. Group basically groups values together
    4. Note: Lists are not mutable in scheme
    5. Vocab
      1. Data Abstraction: groups compound information into units to be accessed and manipulated
      2. Constructor: a procedure that creates a data abstraction
      3. Selector: accesses and returns some information when a data abstraction is passed into it
      4. Documentation: information or instructions that describe how a data abstraction work
      5. Implementation: how something is coded behind the scenes
  3. Abstraction Barrier
    1. Each layer only uses the layer below it
      1. User program
      2. Data Abstraction
      3. Primitive Representation