[Cuis-dev] extending the syntax for blocks and methods

[Benoit St-Jean]

You mean "currying" as in this?
https://web.archive.org/web/20080106132736/https://blog.3plus4.org/2007/03/23/currying-in-smalltalk/


 

    On Sunday, July 17, 2022 at 01:27:57 a.m. EDT, stephen--- via Cuis-dev <cuis-dev at lists.cuis.st> wrote:  
 
 
I did a hack a while back in VisualWorks (overriding messageNotUnderstood:) so that blocks would understand any messages sent to them as variations of value:value:. If you parse the message that’s not understood, get the number of arguments, and then send the right version of value:value: with the arguments, you can create a block with any number of arguments and use it with any calling method, as in,
 | summer sum | summer := [ :a :b | a + b]. sum := summer add: 1 to: 2.

stp

--
                    Stephen Travis Pope   Ojai, California, USA              http://HeavenEverywhere.com        http://FASTLabInc.com                       https://vimeo.com/user19434036/videos      http://heaveneverywhere.com/Reflections
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On Jul 16, 2022, at 2:51 AM, Luciano Notarfrancesco via Cuis-dev <cuis-dev at lists.cuis.st> wrote:
Hola!Interesting. Actually methods written like this look more complicated than the original Smalltalk-80 syntax to me, but it’s an interesting idea, maybe looks complicated just because I’m not used to it. Let us know how it goes.
Note that in Cuis #: is a valid binary message. I use it, maybe I’m the only one who uses it.
Another idea we discussed before was to compile ‘f(x)’ as ‘f value: x’. Note that this is not ambiguous with Smalltalk-80. We could also compile ‘a[i]’ as ‘a at: i’. I’m not sure if it’s worth to complicate the Smalltalk-80 syntax with things like this, tho, I also value simplicity.


On Sat, 16 Jul 2022 at 01:39 Francisco Garau via Cuis-dev <cuis-dev at lists.cuis.st> wrote:

Hola Amigos -- just wanted to share with you some ideas I've been thinking about for a while. 
It all started when someone mentioned the colon in the syntax for block arguments could have whitespace around the argument so that you could write  [ : n | n + 1] 
It makes perfect sense to see the block as an "inlined" method that doesn't require any method-lookup; therefore, the selector is superfluous. But if we accepted the selector inside the block, it could be used as the variable holding the block. So, instead of writing succ := [:n | n + 1]  we could write  [succ: n | n + 1]  
Even better if the block evaluation accepts #: as a valid selector.  So you could write (succ: 3) = 4 instead of (succ value: 3) = 4. 
A short example will make this clear. 

Vanilla Smalltalk
succ := [:n | n + 1].

(succ value: 3) = 4. 

Extended Block Syntax
[succ: n | n + 1]. 

(succ: 3 ) = 4. 

"the above is equivalent to" 

(succ perform: #: with: 3) = 4. 



Being able to parse blocks with these syntax paves the way to unify the syntax for method definition—for example, a few hypothetical methods from the Point class. 


"Point class>x:y:" 

[x: xInteger y: yInteger | 

   ^self basicNew setX: xInteger setY: yInteger].






"Point>>abs"

[abs | 

   ^x abs @ y abs]. 






"Point>>extent:" 

[extent: aPoint |

   ^Rectangle origin: self extent: aPoint] 


Of course, it gets trickier when blocks have more than one argument.. 


[add: a to: b | a + b]. 

(add_to value: 3 value: 4) = 7. "old style block evaluation" 

(add: 3 to: 4) = 7. 

I think building a separate Parser is a sensible approach -- is there a Smalltalk Parser as a separate package that can be tweaked without affecting the running image?

Thanks,Francisco

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