Hissp/community

Python with a Lissp. https://hissp.rtfd.io Ask, don't ask to ask. Answers may take a day. https://github.com/gilch/hebigo

gilch

@gilch

I've been pushing commits daily, so I'm wondering when a good stopping point for the PyPI release is.

Enough has changed that I want to do it soon, but I at least want the docs to match the code when that happens.

The sphinx theme I'm using is still having issues rendering some things.

The module index page is broken.

I figured out how to doctest the quickstart, and it's uncovered some issues so far. I should have that done in a day or two.

Assuming no more surprises pop up.

Kyle I S Harrington

@kephale

yeah like the clojure airity overloads, but it was more of a passing thought than a pressing need

Kyle I S Harrington

@kephale

the issue is just that the current pypi version isn't usable for code that works with the latest master

i'm certainly fine working on a couple of machines, but its harder to play around with ideas to scale up (not that I'm quite ready for that yet, but could be in a week or so)

gilch

@gilch

Python doesn't have arity overloads built in, but you could implement a dispatcher with a starargs and a cond on its length.

If it's a pattern you use a lot, it wouldn't be too difficult to implement it in terms of that using a macro.

Kyle I S Harrington

@kephale

one thing that i'm getting hung up on is going from tuples to s-expressions

I wanted something like an apply:

(defmacro apply (f : :* args)
    `(operator..add '(,f) ,@args))

and i've tried some variations on that, but the closest result gives me a tuple

gilch

@gilch

Python 2 had an apply, but it was deprecated in 2.3 after they added star unpacking, and was removed in Python 3.

def apply(callable, args=(), kwargs={}):
    return callable(*args, **kwargs)

That's a function, not a macro.

I'm not exactly sure what you're trying to do with that template. Maybe you could clarify with an example input and output?

Kyle I S Harrington

@kephale

(apply + '(1 2))

that is a pattern I use a lot (not just for math, but that is the easy example)

gilch

@gilch

So you want a macro to transform (apply + '(1 2)) into (+ 1 2)?

Kyle I S Harrington

@kephale

yeah

and evaluate it

i believe that will give coverage of all cases of map-reduce

gilch

@gilch

(defmacro apply (f xs)
  `(,f ,@(cadr xs)))

apply is normally a function as I demonstrated in the Python def above.

Macros get all of their arguments quoted. Because they run at compile time, their arguments haven't been evaluated yet.

So passing '(1 2) means it's quoted twice.

Kyle I S Harrington

@kephale

hmm ok

ah yeah that cadr fix does it

ok i'll do some comparisons with a python implementation as well

gilch

@gilch

So you have (quote '(1 2)) and only want the '(1 2).

If you had called it with (apply + (1 2)), then you wouldn't have to strip the quote.

Kyle I S Harrington

@kephale

yeah, i see, but i would get confused without the '(1 2)

gilch

@gilch

Yeah, apply is supposed to be a function, so it can get evaluated arguments.

Kyle I S Harrington

@kephale

:thumbsup:

thank you!

gilch

@gilch

You can certainly expand a macro to a function call though.

(defmacro apply* (f xs)
  `(apply ,f ,xs))

Assuming that Python definition.

Which you could write in Hissp as

(define apply
  (lambda (callable : args ()  kwargs {})
    (callable : :* args  :** kwargs)))

Or inline it like

Kyle I S Harrington

@kephale

i think that define is exactly what i was after!

gilch

@gilch

(defmacro apply (f xs)
  `((lambda ($#f $#xs)
      ($#f : :* $#xs))
    ,f ,xs))

There's really no difference between s-expressions and tuples in Lissp like there is in Hy. A quoted s-expression compiles to a tuple, and s-expressions read as Hissp tuples.

Whereas Hy has a separate HyExpression type.

gilch

@gilch

If I recall, Clojure's apply was a bit different.

Kyle I S Harrington

@kephale

thats what I thought (yeah the HyExpressions really threw me off). I kept ending up with results that were tuples, but I think I was missing a deeper concept

but Clojure's apply can work the same way at least

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