Re: [stack] Concatenative Research

On 1 Feb 2011, at 13:02, John Carter wrote:

> On Mon, Jan 31, 2011 at 6:11 PM, Justin <[email protected]> wrote:
> 
> >
> >
> > > What may be interesting and useful would be to return to typed variables
> > > (named values variety) and something like a SQL "natural join".
> >
> > I don't know what you mean. Could you give an example? (I don't have a good
> > mental model of databases.)
> >
> 
> The truely irritating thing about both stack languages, and the more
> traditional languages with named parameters, is that the order of the
> parameters and the names don't really matter.
> 
> Given any program P in a stack or traditional language, you can reorder
> and/or rename the parameters of every function anyway you choose... and come
> up with another program that does EXACTLY the same thing, so long as you
> carry through the renaming through the the body of each function and the
> reordering into every invocation of the function.
> 
> In stack languages without parameter names, your program will _look_
> radically different as there will be a flock of stack manipulation operators
> different.
> 
> ie. In a very strong sense, parameter names and parameter order is fluff and
> irrelevant to the actual computation being performed!
> 
> Thus my mathematical gut feeling is, one should be able to eliminate it
> _all_ in some representation.
> 
> I could be unconstructive an give you a lmgtfy link about natural joins, but
> let me rather discard the SQLish analogy and try say what I mean in a
> stackish language.
> 
> Well, a lot of stack languages (Factor is a very good example) give the
> stack effect for each function as something like...
> 
> fn: T1, T2, T3... -> T4, T5... where I mean fn is a function that pops
> parameters of type ..., T3, T2, T1 off the stack, in that order and pushes
> objects of type T4, T5, .. onto the stack in that order.
> 

Given only this, shouldn't the inner interpreter be able to perform stack shuffling between function calls automatically?
--
don



> 
> Well, lets add some names...
> 
> fn: i1 T1, i2 T2, ...-> o4 T4, o5 T5, ...
> 
> Where I am naming my input parameters i1, i2, ... and my output values as
> o4, o5, ...
> 
> Now a fragment of any stack language code tends to look like....
> 
> fn1 stackOp1 stackOp2, ... fn2
> 
> where all the stackOps rearrange the stack as it was left by fn1 and it's
> predecessors, so as to feed fn2 correctly.
> 
> However, it you were to look at the stack effect declarations for fn1, and
> fn2, it would probably be obvious from the types alone, as which stackOps
> you would need between fn1 and fn2!
> 
> And if the types alone weren't enough to tell you, the names certainly
> would!
> 
> Thus in principle one could create a language where you could write a
> fragment as fn1 fn2 and the compiler could infer what stackOps (or calling
> parameters and their order) are required.
> 
> -- 
> John Carter Phone : (64)(3) 358 6639
> Tait Electronics Fax : (64)(3) 359 4632
> PO Box 1645 Christchurch Email : [email protected]
> New Zealand
> 
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