[squeak-dev] Not Squeak but... Ni goes multithreaded

Göran Krampe goran at krampe.se
Tue Feb 2 15:44:46 UTC 2016


On 02/02/2016 02:48 PM, David T. Lewis wrote:
> Cool.
> Are the numbers in the factorial example values on the stack, or are
> they "objects" in the Smalltalk sense? I'm curious how Ni might be
> approaching a shared object space for the interpreters.

In Ni everything is a "node" as in an AST Node. ints and floats are 
boxed Nim ints/floats. Strings are boxed Nim strings and blocks are 
boxed Nim seq (dynamic array). Dictionaries are boxed Nim OrderedTables. 
true, false, nil and undef are singleton objects.

So they are Nim objects (which means the VM can actually do dynamic 
dispatch on them using Nim's mechanism for that) but in Ni they are 
"primitive types".

BUT... the model I am working on for "OO" in Ni is centered around 
instance tagging (!) and dynamic dispatch using these tags of Ni funcs. 
Since everything (ints floats etc) are nodes, they can be tagged and 
thus "methods" can be polymorphically dispatched on everything.

And since Ni (just like Nim) offers "infix functions with more than one 
argument, optionally using keyword syntax" you should get a very OO-ish 

So Ni uses Nim objects for the AST nodes and thus also uses Nim's GC (it 
has 5 different ones!). The reified stack is also built with Nim objects 
as a spaghetti stack so it too is GCd by Nim.

Nim has several interesting things going in the multithreading space. It 
has an asynch model and it also has channels one can use between native 
threads - the latter is used in a very nice article that Dennis Felsing 
just wrote:


In fact, Dennis blog has a whole slew of brilliant Nim articles.

Exactly how Ni will piggy back on all these options is unclear at this 
point - and oh, it uses FlowVars too.

But do note that the Nim GC runs *per thread* so to do memory sharing 
between native threads in Nim you would need to use special shared 
constructs. However... stuff is brewing in that area too in Nim.

But generally I am inclined towards a shared nothing model between 
native threads (as I have now) but perhaps implementing coroutines or 
something within a single thread. That is also why I need to go 
stackless, so that I can manipulate the Ni stack without being hindered 
by the Nim (C) stack.

regards, Göran

PS. I am still waiting for someone to join me in this coding adventure. 
:) This is fresh ground here, but we have a tremendous solid base in the 
Nim eco system.

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