"Truthy pipe" syntax proposition
akx opened this issue · comments
For a lark, I wanted to see what some Django ORM code might look like in Coco and ended up with
object-list =
Category.objects.language instance.language
|> if category = instance.category then &filter {category} else &
|> &slice instance.count
-- this works alright, but the second line of the chain is kinda ugly because of the else branch.
So I'd propose a "truthy pipe" syntax, perhaps ?>, so any falsy values in that block would be emitted as & instead.
object-list =
Category.objects.language instance.language
?> (&filter {category} if category = instance.category)
|> &slice instance.count
Currently, with Coco 0.9, with |> instead of ?> the following JS is emitted (I've added some linebreaks for readability), and obviously the "void 8" emitted as the implicit "else" breaks the chaining.
var objectList, x$, category;
objectList = (
x$ = Category.objects.language(instance.language),
x$ = (category = instance.category) ?
x$.filter({category: category}) :
void 8,
x$.slice(instance.count)
);
In addition I wouldn't mind it if ?> had a slightly different precedence so the parentheses in the post-if wouldn't be necessary...
A new operator solely for omitting at most 7 bytes in a narrow situation sounds overkill.
Closing for the reason above.
I wouldn't mind it if
?>had a slightly different precedence so the parentheses in the post-if wouldn't be necessary...
As for this issue, |> is given the lowest precedence present (as I didn't want to create yet another level) which happens to be the same as post-if. May have been a mistake considering expressions like a |> b if c |> d unintuitively evaluates as ((a |> b) if c) |> d.
On a single line, isn't it going to conflict with post-if specialcase ?
What specialcase exactly?
The brace-insertion for implicit objects kicks in before the parser job. They may seem to interact oddly, but not in a conflicting way.
I don't really get what happens in cases like a |> b c: d |> foo if bar.
It goes:
a |> b {c: d |> foo} if bar
↓
a |> b({c: d |> foo}) if bar
↓
a |> (b({c: d |> foo}) if bar)
Hm. Probably |> should also close inline implicit objects.
Yeah, that's what I thought.