Fundamentals of Functional Programming

• What are the features of functional programming?

  • Statelessness and Immutability
  • Functions are used as the fundamental building blocks
  • No side affects
• What is a function

  a rule that for each element of some set A of inputs, assigns an output chosen from a set B but without necessarily using every member of B.
• What is a domain?

  A domain is a set from which the function's input values are chosen
• What is a co-domain

  a set from which the functions outputs values are chosen
• What is a first class object?

  something that:

  • Can be assigned to a variable
  • appear in an expression
  • be assigned as an argument
  • be returned in a function call
• Give some examples of first class objects?

  • integers
  • floats
  • characters
  • strings
• What does it mean when functions are refered to as statelesss

  • do not rely on or alter any state outside of their scope
• What is immutability?

  • once a data structure is created, it cannot be changed
• What is functional programming?

  A programming paradigm based on functions
• What defines a higher order function?

  It takes or returns a function
• What does the map function do?

  Applies a function to a list of elements
• If you want to subtract 2 from each element in a list, which function would you use?

  Map function
• What is the purpose of the filter function?

  Returns elements that meet a specific condition
• If you want to keep only elements greater than 1 from a list, which function would you use?

  Filter function
• What does folding a list do?

  Reduces the list to a single value
• What is another name for folding?

  Reducing
• What does the fold function require?

  An operator, a starting number, and a list
• What type of fold will you be asked questions about?

  Fold left
• What is the specification for functional language programs?

  Show experience of constructing simple programs
• What is a higher-order function?


  A function that takes or returns another function
• What does the map function return?

  A list of results after applying a function
• What does the filter function produce?

  A new data structure with matching elements
• What does the reduce or fold function do?

  Reduces a list to a single value
• What is the main focus of the fold function?

  To apply a combining function repeatedly
• What is the difference between fold left and fold right?

  It determines how recursion works
• What is the expected knowledge for using higher-order functions?

  Experience with map, filter, and fold
• What are the key characteristics of higher-order functions?

  • Take a function as an argument
  • Return a function as a result
  • Do both of the above
• What are the steps involved in using the map function?

  1. Provide a function to apply
  2. Provide a list of elements
  3. Return a new list with results
• What are the steps involved in using the filter function?

  1. Provide a condition to check
  2. Provide a list of elements
  3. Return a new list with matching elements
• What are the steps involved in using the fold function?

  1. Provide an operator (e.g., +, -)
  2. Provide a starting number
  3. Provide a list of values
  4. Return a single reduced value
• What is the difference between fold left and fold right?

  • Fold left processes elements from the start
  • Fold right processes elements from the end
• What is the composition of functions?


  • the idea that you can combine two functions in order to get a new function
• What is function application?

  • the process of giving particular inputs to a function
• What is partial function application

  • is the process of decomposing multi-arguments functions into smaller functions with less arguments
• Why can functional programming easily take advantage of parallel processing

  its focus on immutability, pure functions, and the absence of shared mutable state
• Explain the purpose of fold/reduce in functional programming?

  • Fold takes a list of values and returns a single value by applying combining function
• Explain how the function map double [1,2,3,4] works (double x :: x*2)

  • the map applies the double function to each list item
  • the map applies double first the head of the list and then a recursive call is made on the tail of the list