Single vs Double quotes in Julia

Question

What is the difference between single quotes and double quotes in Julia?

Unlike Python, for strings, it doesn't allow single quotes:

> s = 'abc'
syntax: invalid character literal
> s = "abc"
> print(s)
abc

But when trying to single quote a double quote, it's allowed:

> s = '"'
> print(s)
"

What is the single quote use for in Julia? Is there documentation like Python's PEP to explain for reason why single quotes are not used?

Answer 1

Think of it like in C/C++; a single quote makes a Char, while double quotes make a String (see, e.g., here).

julia> c = 'a'
'a'
julia> typeof(c)
Char
julia> s = "a"
"a"
julia> typeof(s)
String
julia> s = "ab"
"ab"
julia> typeof(s)
String

In Python we just use a string of length one as characters, but Julia distinguishes between them, and so we get

julia> typeof("abc"[1:1])
String    
julia> typeof("abc"[1])
Char

even though in Python we have

>>> type("abc"[0:1])
<type 'str'>
>>> type("abc"[0])
<type 'str'>