View Source Character Set and Source File Encoding

Character Set

The syntax of Erlang tokens allow the use of the full ISO-8859-1 (Latin-1) character set. This is noticeable in the following ways:

  • All the Latin-1 printable characters can be used and are shown without the escape backslash convention.
  • Unquoted atoms and variables can use all Latin-1 letters.
200 - 237128 - 159Control characters
240 - 277160 - 191- ¿Punctuation characters
300 - 326192 - 214À - ÖUppercase letters
327215×Punctuation character
330 - 336216 - 222Ø - ÞUppercase letters
337 - 366223 - 246ß - öLowercase letters
367247÷Punctuation character
370 - 377248 - 255ø - ÿLowercase letters

Table: Character Classes

The following tokens are allowed to also use Unicode characters outside of the Latin-1 range:

  • String literals. Example: "√π"
  • Character literals. Example: $∑
  • Comments in code.
  • Quoted atoms. Example: 'μs'
  • Function names. Example: 's_to_μs'(S) -> S * 1_000_000.

Atoms used as module names, application names, and node names are restricted to the Latin-1 range.


Support for Unicode in string literals, character literals, and comments was introduced in Erlang/OTP R16B. Support for Unicode in atom and function names was introduced in Erlang/OTP 20.

Source File Encoding

The Erlang source file encoding is selected by a comment in one of the first two lines of the source file. The first string that matches the regular expression coding\s*[:=]\s*([-a-zA-Z0-9])+ selects the encoding. If the matching string is an invalid encoding, it is ignored. The valid encodings are Latin-1 and UTF-8, where the case of the characters can be chosen freely.

The default Erlang source file encoding if no valid coding comment is present is UTF-8.

Two examples, both selecting Latin-1 as the source file encoding:

%% For this file we have chosen encoding = Latin-1
%% -*- coding: latin-1 -*-


The default encoding for Erlang source files was changed from Latin-1 to UTF-8 in Erlang/OTP 17.0.