Skip to Main Content
Think Julia
book

Think Julia

by Ben Lauwens, Allen B. Downey
April 2019
Beginner content levelBeginner
295 pages
5h 48m
English
O'Reilly Media, Inc.
Content preview from Think Julia

Chapter 12. Tuples

This chapter presents one more built-in type, the tuple, and then shows how arrays, dictionaries, and tuples work together. It also introduces a useful feature for variable-length argument arrays, the gather and scatter operators.

Tuples Are Immutable

A tuple is a sequence of values. The values can be of any type, and they are indexed by integers, so in that respect tuples are a lot like arrays. The important difference is that tuples are immutable and that each element can have its own type.

Syntactically, a tuple is a comma-separated list of values:

julia> t = 'a', 'b', 'c', 'd', 'e'
('a', 'b', 'c', 'd', 'e')

Although it is not necessary, it is common to enclose tuples in parentheses:

julia> t = ('a', 'b', 'c', 'd', 'e')
('a', 'b', 'c', 'd', 'e')

To create a tuple with a single element, you have to include a final comma:

julia> t1 = ('a',)
('a',)
julia> typeof(t1)
Tuple{Char}

A value in parentheses without comma is not a tuple:

julia> t2 = ('a')
'a': ASCII/Unicode U+0061 (category Ll: Letter,
  lowercase)
julia> typeof(t2)
Char

Another way to create a tuple is using the built-in function tuple. With no argument, it creates an empty tuple:

julia> tuple()
()

If multiple arguments are provided, the result is a tuple with the given arguments:

julia> t3 = tuple(1, 'a', pi)
(1, 'a', π = 3.1415926535897...)

Because tuple is the name of a built-in function, you should avoid using it as a variable name.

Most array operators also work on tuples. The bracket operator ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Practical Julia

Practical Julia

Lee Phillips
Getting Clojure

Getting Clojure

Russ Olsen
Learning Go

Learning Go

Jon Bodner

Publisher Resources

ISBN: 9781492045021Errata PageSupplemental Content