List functions

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Lecture 1 - Page 15 : 49

Programming Paradigms
Introduction to Functional Programming in Scheme

List functions

There exists a number of important List functions in Scheme, and we often write other such functions ourselves

We will here take a look at some of the most important list functions, as defined by the language itself. You are encouraged to read about them in the Scheme Report, to which we make a reference below.

(null? lst) A predicate that returns whether lst is empty

(list? lst) A predicate that returns whether lst is a proper list

(length lst) Returns the number of elements in a proper list lst

(append lst1 lst2) Concatenates the elements of two or more lists

(reverse lst) Returns the elements in lst in reverse order

(list-ref lst k) Accesses element number k of the list lst

It should be noticed that the first element is designated as element number 0. Thus (list-ref '(a b c) 1) returns b

(list-tail lst k) Returns the k'th tail of the list lst

And many more

R5RS: Pairs and Lists

Lists are passed by reference to the functions that manipulate them