From: shevegen@...
Date: 2014-09-30T13:10:25+00:00
Subject: [ruby-core:65329] [ruby-trunk - Feature #9999] Type Annotations

Issue #9999 has been updated by Robert A. Heiler.


I like the principal idea behind it.

For instance, today I wrote ruby code like this (yes, hate me for using set_ methods
but I like it visually because my brain works that way):

  def set_be_verbose(i)
    @be_verbose = i
  end

@be_verbose can only be true or false, and must never be any value.

It can also only be modified through that accessor method above.

I thought it would be nice if I could somehow tell ruby to check automatically.

Of course I could check the input for FalseClass or TrueClass or something
but I wondered if it would not be better to also provide an additional
OPTIONAL way.

At any rate, I like the idea behind this - my main concern is only the
syntax.

The syntax proposal:

  def connect(r -> Stream, c -> Client) ->  Fiber

I am sorry, that is awful. It would conflict with my ruby code (I do not
use ->) and the intent is not clear at all to me.


  def connect(Stream r, Client c) -> Fiber 

This is a bit better but it also uses -> and thus it really is not good
at all.

If we would not have to be backwards compatible we could use @@ hehe :)

At any rate, please consider the syntax! I picked ruby because it is
by far the most elegant language out there (actually, that is not 
completely true, I picked ruby over python because of its philosophy
from matz' old interview from back then at: http://www.artima.com/intv/ruby.html
it really still is my favourite interview from matz hehe)



----------------------------------------
Feature #9999: Type Annotations
https://bugs.ruby-lang.org/issues/9999#change-49144

* Author: Davide D'Agostino
* Status: Assigned
* Priority: Normal
* Assignee: Yukihiro Matsumoto
* Category: 
* Target version: 
----------------------------------------
Hi all,

I know @matz is interested in introducing **type annotations** in ruby. More here: https://bugs.ruby-lang.org/issues/5583

I think it's time for ruby to get this.

Before working on a patch I would like to know:

1. Syntax of methods signatures
2. Syntax of variables guards (?)
3. Implementation

For point **1** I was thinking in some like:

~~~ruby
def connect(r -> Stream, c -> Client) ->  Fiber
def connect(Stream r, Client c) -> Fiber # quite sure this will make some reduce problems in the grammar
~~~

Before making a proposal consider: keyword arguments and default value collisions.

Then for point **2** I'm not sure if we want also check assignments but as before a syntax could be:

~~~ruby
r: Client = something # will throw an exception if something is not kind of Client
~~~

Finally, **implementation**. Do we want some in python style and then leave the programmer/library for the implementation **or** (and I'm for this) we want MRI do that, if so how?

Cheers!
DD

p.s. Sorry if this issue was already discussed but I didn't find anything except the link posted.



-- 
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