Szathmáry László honlapja @ DEIK | Nim2 / Mutable or immutable?

In Python, a string is immutable.

In Nim, a string can be mutable (var) or immutable (let). It depends on how you declare it.

Immutable

let s = "hello"

echo s # "hello"

echo s[0] # 'h'

s[0] = 'H' # ERROR!

Like in Python.

var s: string

echo s # "" , empty string

s.add("hello")

echo s # "hello"

s[0] = 'H'
echo s # "Hello"

s.add(" World!")

echo s # "Hello World!"

As you can see, it also works as a stringbuffer! We don't need a special StringBuffer type in Nim. Just use a mutable string for this purpose.