What could be slow, repeatedly requesting the "args"
field. Maybe I should do:
help = term.args
i = 0
while i < len(help) - 1:
____mark_term(help[i])
____i += 1
term = help[i]
Mostowski Collapse schrieb am Mittwoch, 15. September 2021 um 20:48:31 UTC+2:
> And how do you iterate over the first n-1 elements
> of a list with n elements? This is what my code does:
> i = 0
> while i < len(term.args) - 1:
> ____mark_term(term.args[i])
> ____i += 1
> term = term.args[i]
> You can try yourself:
>
> % python3
> >>> foo = ["a", "b", "c"]
> >>> i = 0
> >>> while i < len(foo) - 1:
> ... print("mark_term", foo[i])
> ... i += 1
> ...
> mark_term a
> mark_term b
> >>> foo = foo[i]
> >>> foo
> 'c'
> alister schrieb am Mittwoch, 15. September 2021 um 20:41:12 UTC+2:
> > On Wed, 15 Sep 2021 11:31:48 -0700, Mostowski Collapse wrote:
> >
> > > There is a further problem with this:
> > >
> > >> for i,term in enumerate(term.args):
> > >> ____mark_term(term.args[i])
> > >
> > > It should read:
> > >
> > > for i,help in enumerate(term.args):
> > > ____mark_term(help)
> > >
> > > But then i isn't need.
> > even Better (i had only skimmed the code as I was certain I would find
> > this, it is probably the No. 1 thing new python programmers get wrong
> > if your example is correct the it can be simplified even further to
> >
> > for help in term.args:
> > mark_term(help)
> >
> > & if help does not get used after this loop then a comprehension is even
> > better
> > _ == [mark_term(help) for help in term.args]
> >
> >
> > the underscore character is python convention for an unneeded place-
> > holder variable.
> > >
> > > Mostowski Collapse schrieb am Mittwoch, 15. September 2021 um 20:22:50
> > > UTC+2:
> > >> Do you mean, replace this:
> > >> i = 0 while i < len(term.args) - 1:
> > >> ____mark_term(term.args[i])
> > >> ____i += 1 term = term.args[i]
> > >>
> > >> By this:
> > >>
> > >> for i,term in enumerate(term.args):
> > >> ____mark_term(term.args[i])
> > >>
> > >> This wouldn't be correct anymore. The recursive call is only for the
> > >> arguments except for the last one one.
> > >> alister schrieb am Mittwoch, 15. September 2021 um 20:17:23 UTC+2:
> > >> > On Wed, 15 Sep 2021 18:23:10 +0200, Mostowski Collapse wrote:
> > >> >
> > >> > > I really wonder why my Python implementation is a factor 40 slower
> > >> > > than my JavaScript implementation.
> > >> > > Structurally its the same code.
> > >> > >
> > >> > > You can check yourself:
> > >> > >
> > >> > > Python Version:
> > >> > > https://github.com/jburse/dogelog-moon/blob/main/devel/runtimepy/
> > >> > machine.py
> > >> > >
> > >> > > JavaScript Version:
> > >> > > https://github.com/jburse/dogelog-moon/blob/main/devel/runtime/
> > >> > machine.js
> > >> > >
> > >> > > Its the same while, if-then-else, etc.. its the same classes
> > >> > > Variable, Compound etc.. Maybe I could speed it up by some details.
> > >> > > For example to create an array of length n, I use in Python:
> > >> > >
> > >> > > temp = [NotImplemented] * code[pos]
> > >> > > pos += 1
> > >> > >
> > >> > > Whereas in JavaScript I use, also in exec_build2():
> > >> > >
> > >> > > temp = new Array(code[pos++]);
> > >> > >
> > >> > > So I hear Guido doesn't like ++. So in Python I use +=
> > >> > > and a separate statement as a workaround. But otherwise,
> > >> > > what about the creation of an array,
> > >> > >
> > >> > > is the the idiom [_] * _ slow? I am assuming its compiled away. Or
> > >> > > does it really first create an array of size 1 and then enlarge it?
> > >> > >
> > >> > > Julio Di Egidio wrote:
> > >> > <sniped due to top posting>
> > >> >
> > >> > this is probably a string contender
> > >> >
> > >> > i = 0 while i < len(term.args) - 1:
> > >> > mark_term(term.args[i])
> > >> > i += 1 term = term.args[i]
> > >> >
> > >> > try replacing with something more pythonic
> > >> >
> > >> > for index,term in enumerate(term.args):
> > >> > mark_term(term.args[i])
> > >> >
> > >> >
> > >> > & possibly go all the way to changing it into a comprehension
> > >> >
> > >> > there are other similar anti patterns throughout this code.
> > >> >
> > >> > any time you are manually keeping a counter as an index into a
> > >> > list,tupple other iterable YOU ARE DOING IT WRONG!
> > >> >
> > >> > Do not write javascript in python, write python
> > >> >
> > >> >
> > >> >
> > >> > --
> > >> > Two percent of zero is almost nothing.
> > >> >
> > >> >
> > >> >
> > >> >
> > >> > --
> > >> > Whoever dies with the most toys wins.
> > --
> > Pie are not square. Pie are round. Cornbread are square.
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