Mill Computing, Inc. Forums The Mill Tools Simulators Simulation Reply To: Simulation

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Ralph: Just looking at those constraints, I think that modifying Forth might be an easier language to bootstrap. Here are some of the basic modifications:

*** Edit: How do you format text on this board?

Operations would read existing belt data, and add new values
Would operations be able to address the belt, or would there be a belt “PICK” operation to put previous items onto the front of the belt?
Former would be more Mill-ish, latter would be more Forth-ish
Even in the Mill-ish form, addressing the stack would be optional, defaulting to the front of the belt
Addressing the stack should be able to be done via label, not just depth

    lit 1   \ push a literal number
    lit 3
 x: add     \ Declares 'x' to be the location on the belt holding the (first?) return value of this instruction
    lit 4
    add x   \ References wherever on the belt 'x' was.  The other parameter defaults to the front of the belt.
    sub y,0 \ Numeric references are a belt depth.  Does this look too much like subtracting the literal number zero?

If ‘lit’ is properly hidden by the parser, then it could look more Forth-like instead of asm-like, but need to delineate the parameter references:

  1 3 x: add
  4 add (x) sub (y 0)  \ Parens are a little un-forthy
  4 add ^x sub ^y ^0   \ Decorate each reference instead of the beginning/end tokens?

No sharing of stack data between functions, except parameters and return values
Function declarations would have to specify the number of params & returns
Can’t be variable, unless there’s vararg lists in memory, which I wouldn’t bother with
This limits a number of clever operations and could bloat up user code

Dynamic types
The compiler would likely need simple type inference to figure out which typed instruction to generate for ‘add’ etc
Could either foist that on the user, or does the specializer do some of this?
Forth foists it on the user, so might as well do that here

I think building on this basic thinking, of applying Mill-isms to Forth instead of vice-versa, would yield a simple usable bootstrapping language. I think it would end up looking a fair amount like GenAsm, though.

  • This reply was modified 9 years, 5 months ago by  David.