[erlang-questions] A proposal for Unicode variable and atom names in Erlang.

Fred Hebert <>
Mon Oct 22 14:29:51 CEST 2012

Regarding the use of Unicode in variables, here is a short list of 
languages that allow it:

- Ada
- C#
- Common Lisp
- D
- Delphi
- GNU Forth (other impls are often ASCII only)
- Go
- Haskell
- J
- Java
- Mathematica
- Perl (also Perl 6)
- Python
- Racket
- Tcl

Now in any of these languages, can you blame the use of Unicode in 
identifiers as the source of woes in there? Is it usually due to 
semantics, other syntax, lack of clarity (even in English), their 
community? Name me one language where unicode support is a true problem 
compared to anything else, in this list.

Is a Chinese programmer suddenly typing with her own glyphs rather than 
pinyin a problem? If I'm programming in French already and had my 
education in French, it's possible I learned everything using French 

tableau -> array, arbre binaire -> binary tree, liste -> list, paquet -> 
packet, octet -> byte, taille -> size, fichier -> file, dossier -> 
directory, boucle -> loop

and so on. Note that I can use all of these in my existing Erlang 
programs if I want to, if I'm working with people who do not speak 
English  but still have a formal education in Computer Science, software 
engineering, or whatever. Chances are that someone who doesn't speak 
French won't have the best time reading that code, but has it been a 
major problem so far? Would allowing, say accented characters so someone 
can write 'colonne' and 'rangée' instead of 'colonne' and 'rangee' for 
'column' and 'row', be the straw that breaks the camel's back? Is the 
use of accents what's going to be the problem here? Or are we supposed 
to be especially afraid of non-latin-looking characters?

I've mentioned to a few people here before that I'm coming from a small 
part of Quebec where people don't speak English that well. I've had to 
work on code bases where French was mandatory because otherwise, people 
on your team wouldn't be able to understand what the code was supposed 
to do. French code shoved in English exists, and it's being used. I'm 
sure you know the same happens in a boatload of other languages.

Telling these people "well just Learn English, that's what I did when I 
needed to" isn't a valid way of doing things. Nobody should have to jump 
through the hoops we had to jump through, just because we had to when we 
were learning. This isn't a reason enough. I'm not willing to go back to 
my old office, and tell this father of 3 children (who programs to feed 
them) "Sorry buddy, you're out of a job because apparently English is 
now necessary." It just won't happen because it is *not* necessary to 
know English to program.

As much as the huge github love circle and "code is global" thing has 
been going, there's still an entire localized world out there where 
people work in small private enterprises, providing local services to 
people who speak their language, a place where people don't give a shit 
whether user 'robocop56' stars your repository or not. Programmers who 
want to go global can still write English stuff all the same, lest they 
want to see their code shunned by the majority of the world. That's 
likely what anyone using the listed languages above did.

This is no excuse to make it hard for everyone else to work in a way 
they're comfortable. A huge part of programming is being able to reason 
about code. Let programmers who want to do it, be able to do so, 
especially when we see that so many languages support it already, 
without most people even noticing.

Here's one for you specifically Yurii: why would you want to keep people 
from using a feature they want to use but that you wouldn't use anyway?


On 12-10-22 1:08 AM, Yurii Rashkovskii wrote:
> Richard,
> Please excuse my ignorance, but can you name a single good reason for 
> non-latin atoms and variable names? From my personal point of view, 
> this is a sure road to hell.
> How would you read these pieces of code:
> ????1 = length(??1)
> [?|?]
> ?
> Isn't it a blessing that we all are using a fairly short and commonly 
> known alphabet and are able to communicate with each other, 
> collaborate on open source projects, etc.?
> Also, with regards to Unicode support, isn't the most important 
> problem in handling external strings --- i.e. data your system 
> receives from outside?
> Thanks,
> Yurii.
> On Thursday, October 18, 2012 11:07:05 PM UTC-7, Richard O'Keefe wrote:
>     If it were still possible to submit EEPs in plain text,
>     this would be an EEP.  If someone else would like to
>     package this up as an EEP and submit it (under their
>     name, mine, or both), feel free.
>     Forces:
>      (1) Support for Unicode continues to increase, with
>          minimal source code support about to arrive.
>      (2) Unicode variable names and unquoted atoms are not
>          here yet, so now is the time to settle on a design.
>      (3) They will need to come.  There may be legal or
>          institutional reasons why unicode-capable languages
>          are required.  Some people just want to use their
>          own language and script.  Erlang's strength in
>          network applications means that being able to
>          represent Internationalized Domain Names as unquoted
>          atoms would be just as much of a convenience as
>          being able to represent ASCII domain names like
>     www.example.com <http://www.example.com> (which needs no quotes in
>     Erlang) is.
>      (4) There is a framework for Unicode identifiers in
>          Unicode standard annex 31 (UAX#31), and several
>          programming languages, including Ada, Java,
>          C++, C, C#, Javascript, and Python (section 2.3 of
>     http://docs.python.org/release/3.1.5/reference/lexical_analysis.html
>     <http://docs.python.org/release/3.1.5/reference/lexical_analysis.html>
>          and see also http://www.python.org/dev/peps/pep-3131/
>     <http://www.python.org/dev/peps/pep-3131/>
>      (5) Existing Erlang identifiers should remain valid,
>          including ones containing "@" and ".".
>      (6) Existing Erlang support features, such as ignoring
>          names of the form [_][a-zA-Z0-9_]* when reporting
>          singleton variables, should not be broken.
>      (7) We should not "steal" any characters to use as "magic
>          markers" for variables because they might be needed for
>          other purposes.  A good (bad) example of this is "?", which
>          could be used for several things if it were not used for macros.
>     Reference
>         Names of sets of characters, XID_Start, XID_Continue, Lu, Lt,
>     Lo, Pc,
>         Other_Id_Start, are drawn from Unicode and UAX#31.
>             Lu = upper case letters
>             Lt = title case letters
>             Pc = connector punctuators, including the low line (_) and
>                  a number of other characters like undertie (?).
>             Other_Id_Start = script capital p, estimated symbol,
>                  katakana-hiragana voiced sound mark, and
>                  katakana-hiragana semi-voiced sound mark.
>     Variables
>         variable ::= var_start var_continue*
>         var_start ::= XID_Start ? (Lu ? Lt ? Pc ? Other_Id_Start)
>         var_continue ::= XID_Continue U "@"
>         The choice of XID here follows Python.  It ensures that the
>     normalisation
>         of a variable is still a variable.  In fact Unicode variables
>     should be
>         normalised.  Unicode has enough look-alike characters that we
>     cannot hope
>         for "look the same <=> are the same" to be true, but we should
>     go _some_
>         way in that direction.
>         Variables in scripts that do not distinguish letter case have to
>         begin with _some_ special character to ensure that they are not
>         mistaken for unquoted atoms.  There are 10 Pc characters in
>     the Basic
>         Multilingual Plane.  The Erlang parser treats a variable beginning
>         with an underscore specially: there will be no complaint if it
>     is a
>         singleton.  There are 9 other Pc characters for which this special
>         treatment is not applied.  Of course, someone might be using fonts
>         that do include say Arabic letters but not say the undertie.
>      We can
>         deal with that by revising the underscore rule.
>             Variable does not begin with a Pc character =>
>                     should not be a singleton.
>             Variable is just a Pc character and nothing else =>
>                     is a wild card.
>             Variable begins with a Pc character followed by a
>             Latin-1 character =>
>                     may be a singleton.
>             Variable begins with a Pc character following by
>             a character outside the Latin-1 range =>
>                     should not be a singleton.
>         Thus ? is a wild-card, ?? is an atom, _?? should not be
>         a singleton, but __?? _may_ be a singleton.  This rule is a
>         consistent generalisation of the existing rule.
>     Unquoted atoms
>         unquoted_atom ::= atom_start atom_continue
>         atom_start ::= XID_Start \ (Lu ? Lt ? Lo ? Pc)
>                     |  "." (Ll ? Lo)
>         atom_continue ::= XID_Continue U "@"
>                        |  "." (Ll ? Lo)
>         Again the choice of XID follows Python, and ensures that the
>         normalisation of an unquoted atom is still an unquoted atom.
>         Unquoted atoms should be normalised.
>         The details of Erlang unquoted atoms are somewhat subtle; I have
>         checked my understanding experimentally.
>     Keywords
>         Keywords have the form of unquoted atoms.  No new keywords are
>         introduced.
>     Specifics
>     -  Any Python identifier or keyword is
>        an Erlang variable or unquoted atom or keyword.
>     -  @ signs may occur freely in variables and unquoted atoms except
>     as the
>        first character, as now.
>     -  dots may not be followed by capital letters, digits, or
>     underscores,
>        as now.
>     -  I am not sure whether modifier letters should be allowed after
>     a dot.
>     -  I am not sure what to do with the Other_ID_Start characters.
>        Script capital p _looks_ like a capital p and even has "capital" in
>        its name.  All other "* SCRIPT CAPITAL *" characters are upper case
>        letters.  Surely it should be allowed to start a variable.
>        The estimated sign looks like an enlarged lower case e; other
>     symbols
>        that look like letters are classified as letters.  You'd expect
>     this
>        to begin an atom.  As for the Katakana-Hiragana voicing marks,
>     I have
>        no intuition whatever.  Assigning the whole group to atoms seems
>        safest.
>     -  All existing variable names and unquoted atoms remain legal, and no
>        new variable or atom forms using only Latin-1 characters have been
>        introduced.
>     Trouble spot
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