Flashcards · 7517 · Topic 12

Fundamentals of functional programming flashcards

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What is a function in functional programming?: A rule that maps each value in its domain to a value in its co-domain, written f: A → B. It has no side effects: the same input always gives the same output.
What does it mean that functions are first-class objects?: They can be assigned to variables, passed as arguments, and returned as the results of other functions.
What is a higher-order function?: A function that takes a function as an argument, returns a function, or both. Examples: map, filter and reduce (fold).
What do map, filter and reduce (fold) do?: Map: applies a function to every item of a list, giving a new list. Filter: keeps the items that meet a condition. Reduce/fold: combines the items into one value using a function, e.g. a sum.
What is partial function application?: Fixing some of a function’s arguments to produce a new function of the remaining arguments, e.g. add 3 gives a function that adds 3 to its argument.
What is function composition?: Combining two functions so that the output of one becomes the input of the other: g ∘ f means apply f, then g.
What are the head and tail of a list?: Head: the first element. Tail: the list of everything after the first element. Head of [4, 3, 5] is 4; tail is [3, 5].