Re: [Python-ideas] Inline assignments using "given" clauses

On Sun, May 13, 2018 at 2:58 PM, Cameron Simpson wrote: > On 13May2018 14:23, Chris Angelico wrote: >> >> On Sun, May 13, 2018 at 2:05 PM, Cameron Simpson wrote: >>> >>> Could someone point me to a post which nicely describes the rationale >>>

Re: [Python-ideas] Inline assignments using "given" clauses

On Sun, May 13, 2018 at 2:05 PM, Cameron Simpson wrote: > On 11May2018 11:40, Jacco van Dorp wrote: >> >> [...] That all said, I would still prefer: >> >> if re.match(stuff) as m: >> >> which is exactly equal to the := in line length and parallels with. >>

Re: [Python-ideas] Inline assignments using "given" clauses

On 11May2018 11:45, Tim Peters wrote: [Gustavo Carneiro] IMHO, all these toy examples don't translate well to the real world because they tend to use very short variable names while in real world [good written code] tends to select longer more descriptive variable names.

Re: [Python-ideas] Inline assignments using "given" clauses

On 11May2018 11:40, Jacco van Dorp wrote: [...] That all said, I would still prefer: if re.match(stuff) as m: which is exactly equal to the := in line length and parallels with. While that may -technically- be a different beast. Yeah, this is my favorite also. Has the

Re: [Python-ideas] Inline assignments using "given" clauses

On Sat, May 12, 2018 at 11:48 PM Steven D'Aprano wrote: > On Sat, May 12, 2018 at 11:04:45PM -0400, Neil Girdhar wrote: > > Another benefit of given compared with := that I just thought of is this. > > Suppose you have a generator like > > > > (expression(f(x), y, z) > >

Re: [Python-ideas] Inline assignments using "given" clauses

On Sat, May 12, 2018 at 11:04:45PM -0400, Neil Girdhar wrote: > Another benefit of given compared with := that I just thought of is this. > Suppose you have a generator like > > (expression(f(x), y, z) > for x in xs > for y in ys(x) > for z in zs(y)) > > With given notation you can optimize:

Re: [Python-ideas] Inline assignments using "given" clauses

Another benefit of given compared with := that I just thought of is this. Suppose you have a generator like (expression(f(x), y, z) for x in xs for y in ys(x) for z in zs(y)) With given notation you can optimize: (expression(f_x, y, z) for x in xs given f_x = f(x) for y in ys(x) for z in

Re: [Python-ideas] Inline assignments using "given" clauses

Are votes cast in Edwin Hewitt's Hyperreals? I had thought python-ideas voted in the domain R rather than *R. :-) On Sat, May 12, 2018, 5:20 PM Stephen J. Turnbull < turnbull.stephen...@u.tsukuba.ac.jp> wrote: > David Mertz writes: > > > Only the BDFL has a vote with non-zero weight. > >

Re: [Python-ideas] A comprehension scope issue in PEP 572

[Nick] >> That's all well and good, but it is *completely insufficient for the >> language specification*. > I haven't been trying to write reference docs here, but so far as > supplying a rigorous specification goes, I maintain the above gets > "pretty close". It needs more words, and certainly

Re: [Python-ideas] Inline assignments using "given" clauses

On 13May2018 00:51, MRAB wrote: On 2018-05-12 22:07, Cameron Simpson wrote: On 06May2018 02:00, Nick Coghlan wrote: Similar to import statements, optional parentheses could be included in the grammar, allowing the name bindings to be split

Re: [Python-ideas] Inline assignments using "given" clauses

On 13May2018 08:55, Chris Angelico wrote: On Sun, May 13, 2018 at 8:47 AM, Juancarlo Añez wrote: My main point here is that "with" works as well as "given" in this form from an English prose point of view. +1 for "with...as", -1 for ":=" About

Re: [Python-ideas] "given" vs ":=" in list comprehensions

On Sun, May 13, 2018 at 10:34 AM, Andre Roberge wrote: > Second example: multiple assignments. > > When we have multiple temporary assignments, the situation can be more > complicated. In the following series of examples, I will start in reverse > order compared to

Re: [Python-ideas] Inline assignments using "given" clauses

On Sun, May 13, 2018 at 10:27 AM, Juancarlo Añez wrote: > >> if (diff := x - x_base) and (g := gcd(diff, n)) > 1: >> return g >> > > I don't see the advantage in that succinctness: > > g = special_gcd(x - x_base, n) > > if g: > > return g > > > The code bases I

Re: [Python-ideas] Inline assignments using "given" clauses

On Sun, May 13, 2018 at 10:06 AM, Neil Girdhar wrote: > >> Take your choice of which you want: >> >> (spam if (mylist := expr) else eggs) + mylist >> ((mylist := expr) if condition else eggs) + mylist >> (spam if condition else (mylist := expr)) + mylist >> >> Of course, in

[Python-ideas] "given" vs ":=" in list comprehensions

Sorry for chiming in so late; I was lurking using google groups and had to subscribe to post - hence this new thread. I gather that *where* has been discarded as a possible new keywords given its use as a function in numpy (

Re: [Python-ideas] Inline assignments using "given" clauses

> if (diff := x - x_base) and (g := gcd(diff, n)) > 1: > return g > > I don't see the advantage in that succinctness: g = special_gcd(x - x_base, n) if g: return g The code bases I work on constantly move towards having the next guy grok what's going on just by reading the

[Python-ideas] Inline changes to context, or PEP572

A new thread just to suggest taking the discussion about PEP572 well beyond python-ideas (PyConn is good for that). The least anyone should want is a language change that immediately gets tagged on the networks as "don't use", or "use only for...", etc. To be honest, I'll likely be on the "don't

Re: [Python-ideas] Inline assignments using "given" clauses

[attributions lost - sorry, but I can't get 'em back] ... >>> Similar to import statements, optional parentheses could be included in >>> the >>> grammar, allowing the name bindings to be split across multiple lines: >>> >>>if diff and g > 1 given ( >>>diff = x - x_base, >>>g

Re: [Python-ideas] Inline assignments using "given" clauses

On Sat, May 12, 2018 at 2:28 PM Steven D'Aprano wrote: > Part 2. > > On Sat, May 12, 2018 at 08:16:07AM -0700, Neil Girdhar wrote: > > I love given compared with := mainly because > > [...] > > * Python has a reputation for being working pseudocode, and given reads > > like

Re: [Python-ideas] Inline assignments using "given" clauses

On 2018-05-12 22:07, Cameron Simpson wrote: On 06May2018 02:00, Nick Coghlan wrote: On 5 May 2018 at 13:36, Tim Peters wrote: If only one trailing "given" clause can be given per `if` test expression, presumably I couldn't do that without trickery.

Re: [Python-ideas] Inline assignments using "given" clauses

On Sat, May 12, 2018 at 1:25 PM Steven D'Aprano wrote: > On Sat, May 12, 2018 at 08:16:07AM -0700, Neil Girdhar wrote: > > > I love given compared with := mainly because > > > > Simpler is better than complex: > > * given breaks a complex statement into two simpler ones, > >

Re: [Python-ideas] Inline assignments using "given" clauses

> LOOK similar, but are subtly different. The current 'with' statement > doesn't create a subscope; the only "context" it creates is regarding > the resource represented by the context manager. For instance, opening > a file in a 'with' block will close the file at the end of the block - > but you

Re: [Python-ideas] Inline assignments using "given" clauses

On Sun, May 13, 2018 at 8:47 AM, Juancarlo Añez wrote: > >> My main point here is that "with" works as well as "given" in this form >> from an English prose point of view. > > > +1 for "with...as", -1 for ":=" > > About affecting existing contexts, it seems that "with..as"

Re: [Python-ideas] A comprehension scope issue in PEP 572

Ah, fudge - I pasted in the wrong "high-level" code. Sorry! The code that's actually being emulated is not > list(i + sum((i := i+1) + i for j in range(i)) > for i in range(5)) but list(i + sum((i := i+1) for j in range(i)) + i for i in range(5)) > ... I have piles of

Re: [Python-ideas] Inline assignments using "given" clauses

On 13May2018 07:07, Cameron Simpson wrote: Similar to import statements, optional parentheses could be included in the grammar, allowing the name bindings to be split across multiple lines: if diff and g > 1 given ( diff = x - x_base, g = gcd(diff, n), ):

Re: [Python-ideas] Inline assignments using "given" clauses

On 2018-05-12 22:42, Chris Angelico wrote: > It's documented. It's guaranteed not to change. > > https://docs.python.org/3/reference/expressions.html#evaluation-order Thanks. That's good to know, though I continue to hope nobody makes a habit of writing code that depends on it. signature.asc

Re: [Python-ideas] Inline assignments using "given" clauses

On 2018-05-12 18:24, Steven D'Aprano wrote: > On Sat, May 12, 2018 at 08:16:07AM -0700, Neil Girdhar wrote: >> I love given compared with := mainly because >> >> Simpler is better than complex: * given breaks a complex statement >> into two simpler ones, > > [snip] > > Nick's syntax is *much

Re: [Python-ideas] Inline assignments using "given" clauses

On Sun, May 13, 2018 at 6:37 AM, Stephen J. Turnbull wrote: > David Mertz writes: > > > Only the BDFL has a vote with non-zero weight. > > "Infinitesimal" != "zero". > > Pedantically yours, Correct, infinitesimal is not zero. This does not contradict David's

Re: [Python-ideas] Inline assignments using "given" clauses

David Mertz writes: > Only the BDFL has a vote with non-zero weight. "Infinitesimal" != "zero". Pedantically yours, ___ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct:

Re: [Python-ideas] Inline assignments using "given" clauses

Part 2. On Sat, May 12, 2018 at 08:16:07AM -0700, Neil Girdhar wrote: > I love given compared with := mainly because [...] > * Python has a reputation for being working pseudocode, and given reads > like pseudocode. := needs to be deciphered by comparison especially in the > complicated cases

Re: [Python-ideas] Fwd: Pattern Matching Syntax

In some sense async and await are like this group you describe, the keyword "await" doesn't have meaning outside a function annotated with "async". The issue I'd have with your proposal is that it requires the "suite" to be an expression-based multi-line statement, ie. where the last statement

Re: [Python-ideas] Inline assignments using "given" clauses

On Sat, May 12, 2018 at 08:16:07AM -0700, Neil Girdhar wrote: > I love given compared with := mainly because > > Simpler is better than complex: > * given breaks a complex statement into two simpler ones, (Foreshadowing: this argument applies to augmented assignment. See below.) I don't see

Re: [Python-ideas] Inline assignments using "given" clauses

On Sun, May 06, 2018 at 02:00:35AM +1000, Nick Coghlan wrote: > 3. You can stick in an explicit "if True" if you don't need the given > variable in the filter condition > > [(fx**2, fx**3) for x in xs if True given fx = f(x)] o_O I'm replying to an email which is a week old. I haven't seen

Re: [Python-ideas] Inline assignments using "given" clauses

I love given compared with := mainly because Simpler is better than complex: * given breaks a complex statement into two simpler ones, which is putting people off in the simple examples shown here (some people are annoyed by the extra characters). However, when given is used in a list

Re: [Python-ideas] Fwd: Pattern Matching Syntax

I find it weird for case statements to be "inside" match statements. There's isn't a statement "group" that works this way right now, AFAIK. This would also be weird: match X: case Y: ... I thought a form based on try would make more coherent: match: suite case x: suite1 else:

Re: [Python-ideas] Fwd: Pattern Matching Syntax

Great! Also emailed you with logistics. On Sat, May 12, 2018, 01:43 Jelle Zijlstra wrote: > 2018-05-11 22:01 GMT-04:00 Robert Roskam : > >> Hey Steven, >> >> I'm also at PyCon. Shall we take this off list and attempt to meet up and >> discuss?

Re: [Python-ideas] A comprehension scope issue in PEP 572

[Tim] > ... > But an assignment expression target name always has the > same scope within a comprehension. [which is a consequence > of the rules - not a rule of its own] Something related to ponder: what's the meaning of the following _without_ the proposed scope change? So the Golden Binding

Re: [Python-ideas] A comprehension scope issue in PEP 572

There's a lot of things in Brendan's email which I disagree with but will skip to avoid dragging this out even further. But there's one point in particular which I think is important to comment on. On Thu, May 10, 2018 at 11:23:00AM -0700, Brendan Barnwell wrote: > One of the great things

Re: [Python-ideas] Python-ideas Digest, Vol 138, Issue 95

Concerning my previous email, Yes, my mistake. I'd forgotten (ironically) that the whole point is that it's an expression itself. So > while (value:=get_next_pool_item()).in_use: >print(value.refcount()) would be the appropriate analogue. Consequently, my example is invalid. A better

Re: [Python-ideas] Inline assignments using "given" clauses

On Fri, May 11, 2018, 17:04 Tim Peters wrote: > [Matt Arcidy] > >> Note Tim came up with a real metric: > >> 2 * count(":=")/len(statement). > >> It's objective. it's just unclear if a higher score is better or worse. > >> However, one could say "a Tim of .3 is considered

Re: [Python-ideas] Inline assignments using "given" clauses

On Sat, May 12, 2018 at 02:37:20AM +0100, Rob Cliffe via Python-ideas wrote: > Yeah, well, I'm totally lost.  Even after trying out this code, and > refactoring it once if not twice, I didn't understand it.  I don't know > what point you're trying to prove, but you seem to have comprehensively