On 13-07-29 04:29 PM, Wojciech Miłkowski wrote:
Hi,
I'm observing rust development for some time, and I must say it slowly
encourages me to use it. Especially the progress from Perl-like syntax
to more sane and quiet form is enjoyable.
That said I wonder why the function definition has form:
fn name(var: type, ...) -> return_type {...}
instead of more unified:
fn name(var: type, ...): return_type {...}
Sigh. Speaking of Perl!
"Larry's First Law of Language Redesign: Everyone wants the colon."
We get this question every now and then, which is perhaps an indication
that we're attracting more people from Scala-land than I expected. I
can't imagine it's converts from Pascal! Let's tally up some function
tycons from the world of languages:
In the "->" column:
Normal Mathematics[1]
Simply Typed Lambda Calculus[2]
C++11 alternative function syntax[3]
Typed Racket[4]
Typed Python[5]
The term-rewrite languages (OBJ, Maude, Q, Pure)
The ISWIM languages (Miranda, Hope, Clean, Haskell, ML, Ocaml, F#)
In the ":" column:
Scala
One older Pike language (Limbo)
The Wirth languages (Pascal, Modula-3, Oberon)
Eiffel and Sather
Our extremely worthy competitors Clay and Nimrod
In the "some form of juxtaposition" column:
C and C++
C#, Java
D
Cyclone
Alef and Go
If the argument's about consistency, I think the consistent thing to do
is to keep ":" as a separator between bindings and types. My eyes get a
little fuzzy guessing the associativity of "let x : fn(T) : U;" in a way
that they do not when reading "let x : fn(T) -> U;". But I suppose
reasonable people could disagre, or phrase the consistency requirement
differently. My math professors would cry.
Do people feel strongly? I think we've many better things to spend time
on, and I'm not certain it won't raise an ambiguity. It'd also break
every single patch, branch and package in progress (and personally, my
heart is with the ISWIMs).
-Graydon
[1] http://en.wikipedia.org/wiki/Function_%28mathematics%29#Notation
[2] http://en.wikipedia.org/wiki/Simply_typed_lambda_calculus#Syntax
[3] https://en.wikipedia.org/wiki/C%2B%2B11#Alternative_function_syntax
[4]
http://docs.racket-lang.org/ts-guide/types.html#%28part._.Function_.Types%29
[5] http://www.python.org/dev/peps/pep-3107/
_______________________________________________
Rust-dev mailing list
Rust-dev@mozilla.org
https://mail.mozilla.org/listinfo/rust-dev
