[swift-evolution] Beyond Typewriter-Styled Code in Swift, Adoption of Symbols

[David Sweeris]

> On Aug 31, 2017, at 4:54 PM, Dave DeLong <delong at apple.com> wrote:
> 
>> 
>> On Aug 31, 2017, at 5:45 PM, David Sweeris <davesweeris at mac.com <mailto:davesweeris at mac.com>> wrote:
>> 
>>> 
>>> On Aug 31, 2017, at 3:17 PM, Dave DeLong <delong at apple.com <mailto:delong at apple.com>> wrote:
>>> 
>>>> 
>>>> On Aug 31, 2017, at 3:58 PM, David Sweeris <davesweeris at mac.com <mailto:davesweeris at mac.com>> wrote:
>>>> 
>>>> 
>>>>> On Aug 31, 2017, at 2:51 PM, Dave DeLong via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>>>> 
>>>>> Just a side observation…
>>>>> 
>>>>> One of the downsides I would put forward to notation like this is it massively increases the barrier to entry for anyone else. I look at that “Reduction.agda” file and wonder if I need to go back to school for a degree in Math just to understand what’s going on.
>>>>> 
>>>>> On the other hand, while using inefficient matrix notation may be more verbose, it is consistent with the other notation used in programming, which means it is more easily understandable for new-comers to the code.
>>>> 
>>>> New-comers from where? I've met more than one mathematician or physicist who claims they can't code because the syntax isn't what they're used to. People with different backgrounds can and do have vastly different ideas about what constitutes an intuitive syntax for any given semantic (which why I disagree with the notion that having more than one spelling for stuff is inherently bad).
>>> 
>>> That’s a fair point, which IMO reinforces the notion that changes like this should be an editor-level feature, and not a code-level feature.
>>> 
>>> An editor can reformat code (using a font with bazillions of ligatures or whatever) in was that you wouldn’t want to necessarily “hard code”.
>> 
>> To clarify, you're suggesting we do something like this?
>> @prettyprint(prefix operator "Σ", /*probably some CSS or something for telling the editor where to position the arguments relative to the operator, whether they're rendered with subscript vs superscript vs normal, etc */)
>> func sum <T: Numeric, S: Sequence> (indicies: S, term: (S.Element) -> T) -> T {
>>   return indicies.reduce(0) { $0 + term($1) }
>> }
>> 
>> Technically speaking, yeah, sure, such a system could be made to work. I don't see it getting much support outside of Xcode, though, unless you can convince other languages to adopt the same convention. We'd want people's choice of display style to be driven by personal preference, not whether they can integrate Xcode into their workflow. Speaking of workflows, how far from "plain text" do you think we can get before people start thinking that you need a mac running Xcode to program in Swift?
>> 
>> - Dave Sweeris
> 
> Perhaps… I’m fully admitting up-front that this is all really hand-wavy and we’re probably veering a bit off-topic, since this is getting more in to “editor-evolution” rather than “swift-evolution”.
> 
> But yes, if an editor had some sort of intrinsic knowledge about the purpose of a line of code, then it could visually “rewrite” a summation function using a Σ. Or if it knew about matrix types, perhaps it could render the matrix in the 2D format that is standard to matrix notation. Or it could replace UIImage(named: “someConstant”) with the rendered image literal, without actually requiring the explicit underlying image literal syntax.
> 
> A grossly simplified comparison is that good markdown editors don’t just show the plaintext for the markdown you’re writing, but will also `stylize` *code* _correctly_ **as** *`you write it`*.

Aside from the bits about matrices and other things that drastically change the line height, the I think that comparison is only grossly simplified from the PoV of an editor's author(s).

What about the issue of different spelling conventions? It's all well and good for the editor to display "pow(x, 2)" as "x²", but I've never used a system where something that's displayed as "x²" isn't typed as "x^2" (of course, now that I've said that, someone will probably come up with 53 counter-examples). If the editor is rendering a line of code like "let y = log₃(sin²(∫x³dx))" and I add a "+ x^2" to the end, it's probably going to take me a while to find the bug because years of math nerdery (sp?) have trained my brain to think that, when I'm "mathing", "x^2" and "x²" are equivalent statements, kinda like they're just written in different fonts or something. Now, clearly the fault would be mine (because, despite all the math symbols, I'd be programming, not mathing), but if we were to get such a system, I bet that mistake would make the list of "Top 10 Bugs Math People Create in Swift", and it it feels antithetical to a language that generally goes out of its way to prevent such simple errors. The only practical solution I can think of is a mechanism for importing a library without its operators (and preferably without a subset of its operators, since a scenario where someone would need `1+2` to mean something other than `3` seems extremely niche).

- Dave Sweeris

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