(I realized that the way defs are parsed now means that each def
(but the last) is first asserted with the wrong definition expression
(it includes the symbol of the following definition at the end) and
then the parser figures out that there's another defintion following
and re-asserts the correct expression. It would be nice to fix that
but it's kind of a PITA. I used to build a list of definitions and
then assert them all at the end. For now there aren't enough defs to
justify the extra work.
As much fun as it was using ? as an operator, now that all the defs live in a text file you don't see it in the Prolog code anymore.
This way I get to use sweet sweet ASCII (except for the ? symbol in the copyright notice.)
...then the branch combinator works as intended. (Although the constraint-based stuff was also cool, it would have captured information from the comparison.)
?- joy(`[32 >] [++] [--] ifte`, Si, So).
Si = [_6598|_6600],
So = [_6598+1|_6600] ;
Si = [_6598|_6600],
So = [_6598-1|_6600] ;
false.
?- sjc(hmm, `[32 >] [++] [--] ifte`).
func(hmm, [A|B], [A+1|B]).
true ;
func(hmm, [A|B], [A-1|B]).
true ;
false.
If the expression isn't 'true' or 'false' atoms then we assume it's a comparison expression and try to check its truth value.
If this fails then it will try both branches, to allow for e.g. compilation. THis almost works, but there's a choice point or something that gets hit before it tries the false path,
?- joy(` [32 >] [++] [--] ifte`, Si, So).
Si = [_2076|_2078],
So = [_2076+1|_2078] ;
wtf? +
Si = [_2076|_2078],
So = [[+], 1, _2076|_2078] ;
Si = [_2076|_2078],
So = [_2076-1|_2078] ;
wtf? -
Si = [_2076|_2078],
So = [[-], 1, _2076|_2078] ;
wtf? branch
Si = [_2076|_2078],
So = [[branch], [++], [--], _2076>32, _2076|_2078] ;
wtf? swap
Si = [_2076|_2078],
So = [[swap, branch], [--], [++], _2076>32, _2076|_2078] ;
wtf? first
Si = [_2076|_2078],
So = [[first, [++], [--], swap, branch], [_2076>32|_2078], _2076|_2078]
etc...
I like them but then you are constrained (pun intended) to only using integers. I'll probably bring them back at some point, either as an alternate implementation or their own commands.
That eliminates all the recursive calls to thun/3 (outside of thun itself, which is tail recursive.) That means that this Joy interpreter is now fully CPS.
All state is contained in the stack and expression, nothing is hidden in the Prolog "call stack".
python -m joy.vui
With PyGame installed that starts the "VUI" on my system. Neat.
The initial joy home (~/.joypy) is not quite compatible with the one set up by the GUI code. One simple way to fix that would be to e,g, make this use ~/.thun instead.
It turns out that the binary_number relation is used in such a way that it needs to be able to backtrack to preprend leading zeros to the list of bits it constructs to automatically build bitfields of a given width (with the collect//2 DCG.)
Allow for "compilation" of new func/3 rules.
Add comment of crude grammar for Joy syntax.
Minor rearrangements.
show_joy_compile uses portray_clause/1.
Things have kind of run away with me. I've been working in Prolog for
the last month or so. I'm not yet sure how to bring it together with the
Python code.
You still can't edit other text files from within the UI, but at least
now you have a place to persist your own definitions over restarts.
I thought about having a [definitions] section in the config INI file,
but for some reason I prefer a separate definitions.txt file. I dunno.
Might change it in future.
Polytypes module folded into types module, with all the actual type
information done when you load the library module. Some definitions can
be inferred from their body expression, others need to be
CombinatorJoyType wrapped. Still to do: loop.
Simon Forman