[erlang-questions] DRY principle and the syntax inconsistency in fun vs. vanilla functions

Michael Turner <>
Fri May 20 06:34:41 CEST 2011


"this particular feature makes perfect sense to me in its current form."

... having arrived, as you said, with experience from e.g., Haskell, having
similar syntax. This is a little like saying, "I had no trouble with riding
a bicycle when I first tried it -- although to be fair, my experiments with
 riding a unicycle gave me a slight head start in terms of skills." As
someone above reported, Clojure dispenses with the need to name the function
for every clause; if you'd only comparable experience had been with Clojure,
you might have found Erlang syntax strangely inconsistent, inconvenient, and
a little hard to learn.

Look, from my experience with Prolog, Erlang's way *also* made perfect sense
to me in its current form. But the arguments I make here apply with almost
equal weight to Prolog anyway -- I found the repetition vaguely annoying at
the time. And the first time I tried to write a multi-clause fun in Erlang I
was hobbled by the preconceptions set both by Prolog and by Erlang's
standard style (and by the spottiness of the official documentation for
multi-clause funs -- I found it first in Joe's book before I found it
online.)

-michael turner

On Fri, May 20, 2011 at 9:57 AM, Daniel Dormont <>wrote:

> Speaking as a relative newb with experience in other languages, I agree.
> Perhaps my experience is unusual (though honestly, I don't think so) in that
> I've spent some quality time with Haskell and Standard ML before coming to
> Erlang, but this particular feature makes perfect sense to me in its current
> form.
>
> What I'd love is to have this in nested functions too. I don't care much
> care about syntactic consistency for its own sake (heck, Perl is one of my
> favorite languages, what does that tell you) so that's not my motivation;
> what excites me is being able to have recursive closures.
>
> dan
>
> 2011/5/19 Frédéric Trottier-Hébert <>
>
>> I don't agree with complaints either -- I have no issue with Erlang's
>> syntax, lisp/scheme/racket's syntax or any other language. The reality,
>> however, is that while programmers can pick up Erlang's syntax quickly,
>> there's still an initial struggle to break what has been committed to muscle
>> memory by many of the people I have taught it to.
>>
>> The syntax might be the scapegoat of the difficulty in learning foreign
>> concepts like functional paradigms, concurrent ideas or pattern matching,
>> but in any case, it is a hurdle that newcomers have to step over. It's not
>> because they can beat challenges that we have to make it harder on purpose
>> by introducing new elements like the alternative function syntax.
>>
>> --
>> Fred Hébert
>> http://www.erlang-solutions.com
>>
>>
>>
>> On 2011-05-19, at 18:49 PM, Edmond Begumisa wrote:
>>
>> >> People already complain that Erlang's syntax is too ugly or complex;
>> >
>> > I've always found this complaint to be rather quibble.
>> >
>> > Programmers have brains that are extremely well adjusted to parsing new
>> syntax. This is one thing all programmers are inherently good at. Yet when
>> asked to put this skill towards learning a new language, they complain. "No"
>> they say, "give me a syntax I'm already familiar with. Why are you trying to
>> be different?" they ask.
>> >
>> > I learned Erlang by reading Joe's book. Within half an hour I wasn't
>> seeing the syntax anymore. My brain, quickly made the necessary mental
>> mappings. I strongly believe this to be the case with all programmers when
>> encountering an unfamiliar syntax -- rapid adjustment with relatively little
>> effort.
>> >
>> > Other professions are not so lucky. I once witnessed two non-programmers
>> trying to learn HTML at the same time. One a medical doctor, the other a
>> graphic designer. Both got the concepts down very quickly (links, images,
>> tables, etc), but both really struggled with syntax. "How can one possibly
>> read this?" they kept asking.
>> >
>> > Yet most programmers learn HTML/XML syntax in a matter of minutes while
>> watching TV. Gut give them Erlang and they groan and complain loudly.
>> >
>> > IMHO, complaints about Erlang's syntax being "too weird" are completely
>> unwarranted. A programmer could learn a language written using Klingon
>> symbols in a unbelievably short period of time. Just look at all those
>> non-English speakers who program in languages heavily biased towards
>> English. And many of them come from languages using non-latin scripts!!!
>> >
>> > - Edmond -
>> >
>> > PS: The exception is Lisp. All those parentheses are just obfuscating :)
>> >
>> >
>> >
>> > On Thu, 19 May 2011 21:41:50 +1000, Frédéric Trottier-Hébert <
>> > wrote:
>> >
>> >> I would rather have one clear but slightly verbose way of doing things
>> rather than two potential ways to do the same thing in slightly different
>> manners prompting religious wars to get the same result I already have.
>> >>
>> >> The idea to revisit the syntax isn't bad in itself, but looking at the
>> examples Steve Davis provided, I can only see your concept being useful for
>> very short functions.
>> >>
>> >> When it comes to learning Erlang, I can tell you that in my experience,
>> new users struggle a lot more with clause separators (;), expression
>> separators (,), form terminators (.), records, 'if' or funs (in concept)
>> than they do with function syntax. They do not seem to see the current way
>> to write function heads as problematic. Then, all Erlang users are also used
>> to it.
>> >>
>> >> Adding more ways to do things that currently have a single way to be
>> done is a net loss in my opinion. People already complain that Erlang's
>> syntax is too ugly or complex; I do not think that adding more syntax is the
>> way to solve that. It would not benefit new users and it would not benefit
>> the majority of all users, only increase the ways they can read code and get
>> confused.
>> >>
>> >> In the other thread, someone called it 'syntactic salt', and I think
>> this is a good way to describe how things are right now. It's not a bad
>> thing in my opinion.
>> >>
>> >> On 2011-05-19, at 06:47 AM, Michael Turner wrote:
>> >>
>> >>> "But how interesting is whether existing code would break or not?"
>> >>>
>> >>> Not very. I mean, who uses Erlang for anything important? Hardly
>> anybody, right?
>> >>>
>> >>> [/sarcasm]
>> >>>
>> >>> "It would, as others have pointed out, also be much harder to jump
>> into a module and _know_ what the clause does since the function's name can
>> be pages away."
>> >>>
>> >>> It would only be harder ("much"??) if you *chose*, in such cases, to
>> use the syntax I propose to bring over from multi-clause funs. In the case
>> you bring up, it might be wiser not to. And what I propose clearly allows
>> everyone to continue with the present syntax. So your argument for
>> readability in this case comes down to "somebody might not use this language
>> feature wisely." (*facepalm*).
>> >>>
>> >>> -michael turner
>> >>> _______
>> >>> erlang-questions mailing list
>> >>> 
>> >>> http://erlang.org/mailman/listinfo/erlang-questions
>> >>
>> >> --
>> >> Fred Hébert
>> >> http://www.erlang-solutions.com
>> >
>> >
>> > --
>> > Using Opera's revolutionary e-mail client: http://www.opera.com/mail/
>>
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