Can someone explain to me what is so horrible about curly braces that we need a whole host of "human-friendly" configuration languages with nontrivial parsing just to get around them?
We are stuck in the old paradigm of characters taking space on the screen and the idea that a markup language must support classic dumb TUI. If, just imagine it, we used some Unicode range for control characters for the semantic markup and standardized UX for it, we wouldn’t need using normal characters as delimiters and escaping them in strings.
The following would have parseable structure, but would be free of visual noise.
Title: Markup languages: decades of going in the wrong direction
Keywords: hypertext,
delimiters,
ˋ, ", \
People have suggested using the control characters for CSV structured files. The problem is that they are impossible to edit.
Control characters are invisible, using them means changing text editors to display them. They are also, outside the usual ones, hard to type. ASCII ones have Ctrl combos, but editors used those for other things.
Also, what is the difference between using some new character to start block and "{" or "\n"? Why have new thing to indicate new level when have space and tab?
Well in that case, it's all the ways that IDEs like to jank up whitespace, as well as the additional difficulty knowing 'context'.
With JSON it's fairly easy for me to know if I want to end my structure as well as the structure containing it, I can just type }}, and add the next element.
With whitespace you have to keep track of HOW MUCH whitespace, and trust me once you've got people who are entirely inconsistent with how much whitespace they use it becomes a huge PITA.
Honestly, nothing. Except the endless debate on where the braces go, and how long they're allowed to stay on a single line.
It seems trivial, but replacing scope delimiters with a per-line signifier (i.e. indent) makes the scope of each line self-contained and sidesteps that discussion.
Is that worth YAYAML (Yet another YAML)? I don't know. But I certainly get the desire to skip the discussion :)
I couldn't help but notice almost immediately one feature that is not human oriented, but most likely exists because it's easier for a machine to parse: single (":") vs double colon ("::"). This is not human-friendly. A human wants to write "key" "is" "value", and YAML has for a very long time supported a single ":" for "is" regardless of the actual type of the value.
I shouldn't have to care about what the type of the value is when writing out effectively YAML. This double-colon feature will do nothing but lead to bug reports from people confused as to why their document is invalid.
The comment above gives explanations defending subjective preferences about what "human oriented" means. That's fine as long as you remember that is what is happening: justification of subjective preferences. Other people can reasonably (or unreasonably) have different subjective preferences.
Also notice what the commenter above haven't done (yet, maybe they will?): done a full "forest level" comparison of all the trade-offs between the current HUML specification and ... what is your alternative proposal, exactly?
Based on my experience, I would guess that most people who design a language (and written a parser for it) for the first time will: (1) be surprised at how quickly design decisions snowball and lead to unexpected places; (ii) discover just how entangled design choices really are; (iii) will give up on trying to please everyone.
In my view, a language designer does really well to describe one's motivations, goals, tradeoffs, decisions, and then live with what you make, because... (a) making something real and useful is rad and (b) any language you make will probably have some weird stank you can't seem to get rid of.
The original designers of YAML explicitly declared in its name "Yet Another Markup Language" that it was designed to be a markup language, which it most certainly was not. Eventually somebody finally pointed out the mistake, and they sheepishly retronymed it "YAML Ain't Markup Language".
On the other hand, and to your points, Relax/NG (both its XML and simplified syntaxes) is a beautiful successful example of wisely and collaboratively designing a new clean powerful system with the deep understanding of what a markup language really is (James Clark was deeply involved with many SGML and XML standards and implementations), and full cognizance of the strengths and weaknesses of other systems you're trying to replace (SGML DTDs, XML Schemas, TREX, RELAX, XDuce, and other experimental XML schema languages).
>In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML—a RELAX NG schema specifies a pattern for the structure and content of an XML document. A RELAX NG schema is itself an XML document but RELAX NG also offers a popular compact, non-XML syntax.[1] Compared to other XML schema languages RELAX NG is considered relatively simple.
Abstract:
RELAX NG is a new schema language for XML. This paper discusses various aspects of the design of RELAX NG including the treatment of attributes, datatyping, mixed content, unordered content namespaces, cross-references and modularity. [...]
>Composability
>RELAX NG is designed to be highly composable. A schema language (or indeed a programming language) provides a number of atomic objects and a number of methods of composition. The methods of composition can be used to combine atomic objects into compound objects which can in turn be composed into further compound objects. The composability of the language is the degree to which the various methods of composition can be applied uniformly to all the various objects of the language, both atomic and compound. For example, RELAX NG provides a choice element that can be applied uniformly to elements, attributes, datatypes and enumerated values. This is not mere syntactic overloading. The choice element has a single uniform semantic in all these cases and can have a single implementation. Another example is the grammar element, which is the container for definitions. The grammar element is just another pattern and can be composed in just the same way as other patterns. Composability improves ease of learning and ease of use. Composability also tends to improve the ratio between complexity and power: for a given amount of complexity, a more composable language will be more powerful than a less composable one. [...]
>XML syntax
RELAX NG uses XML instance syntax to express schemas. Although this makes for a rather verbose schema language, it has some major advantages. Since a user of an XML schema language must necessarily already learn XML instance syntax, using XML instance syntax for the schema language reduces the learning burden on a schema user. It also allows XML tools and technologies to be applied to the schema. For example, a schema can be used to specify the syntax of the schema language. Another important benefit of XML syntax is extensibility. RELAX NG has an open syntax that allows the RELAX NG defined elements and attributes to be annotated with elements and attributes from other namespaces. RELAX NG DTD Compatibility [12] uses this annotation mechanism to extend RELAX NG with a mechanism for declaring default values for attributes. RelaxNGCC [23] uses this annotation mechanism to allow users to embed Java code in RELAX NG schemas, which gets executed as an XML document is parsed against the schema. An unofficial non-XML syntax for RELAX NG has also been developed [8]. The non-XML syntax can be used for authoring RELAX NG schemas by hand and can then be transformed into the standard RELAX NG XML syntax for interchange. [...]
For me, it’s clearer with a double colon. Not intuitive, but extremely easy to get used to. When I see the first colon introduce a list, I have to go out of my way to not see the other colons as introducing lists.
I think we should have a name for the often undue examination and analysis of colon/semicolon usage in machine languages. I volunteer the name "colonoscopy."
> Especially since representing a dict already has 2 ways,
And lists.
> Pythonic
Pythonic in the way that Python's 'There should be one...' is expressed through the existence of tuples, named tuples, dataclasses, regular classes and attrs (not part of the standard library but it seems to be as much of a goto as requests is)? ;)
Slightly off-topic, but I find the text of that anchor fragment amusing ("why? just why?") and a little disappointing. Automatic CMSs have robbed us of attention to detail - that anchor (for "Why `::`?") should probably be changed to `why-double-colon`.
If the goal is to look similar to YAML and fix its problems and assert itself as something that's needed in a world with YAML, the introduction should probably explicitly call out some clear differences.
`::` is quite strange. 1) It only allows to resolve nesting conflicts for a single level. 2) Could be hard to read and could lead to reasoning mistakes. 3) Looks like an attempt to differentiate HUML from YAML somehow.
I do appreciate that they lead with the examples. They convey 90% of the important information. TBH, having worked with yaml just enough to get by with k8s deployments, I could immediately spot how this would be an improvement.
Yeah, I don't disagree. I'd go further and say the examples are on-point for a "human oriented" language. But the formal spec reveals how simple or complicated this language is. (And I'm also writing this from the perspective of someone who uses a programming language that does not have a HOML implementation).
Reminder: you can use indentation to encode s-expressions. The result is very easy to parse and easy to read provided the underlying data structures are not insane.
Data only for JSON, it lacks just like everything else as a configuration language. Arguments against I have seen are too verbose, too strict, and no comments. I am sure there are more.
Oh lord. We already have TOML, which is an improvement on limited JSON when a human-readable, easily-diffable, more flexible format is needed.
We don't even need HCL (offers little value), YAML (has too many features making it inherently less secure), XML (is a mess with too many features and too much verbosity), or INI (insufficient features) except for existing and historical reasons.
In cases where a single file is attempted to be managed by multiple, competing interests, it's probably better to split the file into multiple, modular/include files like *.d/* so there would be less chances for merge conflicts.
And then there's /{proc,sys}-like configuration with one "value" per file where the path forms the heirarchy.
Please. Just. Stop reinventing wheels that were already round enough.
This is the main reason why YAML and Python are bad. Give us CLEAR beginnings and ends to code statements and blocks, not these dubious beginnings and ends. Ignore white space and use clear EOL delineation. Clearly, XML and JSON are superior to YAML and even this weird-looking HUML. Not to mention almost any other language syntax being superior to Python.
There are plenty of times in Python and YAML I cannot visually figure out where some block ends.
JSON prevents this by explicitly closing lists and dicts. Though you do end up with Ladders to Heaven of `}`'s and `]`'s where you have no goddamn clue what is actually being closed out.
XML prevents this by explictly stating what element was just closed. Deeply nested XML, provided the elements don't have some 300 character set of attributes all jammed into the opening element, is vastly easier to read than YAML.
> There are plenty of times in Python and YAML I cannot visually figure out where some block ends.
To match the start of a Python block (with possibly other blocks nested within it) to its end: start at the (non-whitespace) column where the opening line begins, and go straight down until you find another line that starts in that column (or EOF).
You can also just... not nest so deeply, or write so long. My functions rarely have more than ten lines are are usually not even inside classes; and I don't generally need more than three levels of indentation (that gets you, for example, a test within a loop within a function — which might well be better done with a comprehension anyway).
> XML prevents this by explictly stating what element was just closed.
Only for elements that cannot, even indirectly, contain other elements of the same element name. And for this limited safeguard, you double up every element name even in cases where it would otherwise be completely clear (which contributes to visual noise as the sibling comment points out). Of course, XML is designed for things that inherently need to be deeply nested. Your code usually doesn't.
> There are plenty of times in Python and YAML I cannot visually figure out where some block ends.
I might understand this objection for YAML, but for python, it's very clear: a block ends whenever the content on the next line is indented by four fewer spaces. (And lists and dicts are explicitly closed with brackets)
If you're talking about matching block starts to ends, then that's just as bad in json, if not worse; without an editor that does brace coloring, it's almost impossible to eyeball which brace goes to which block without indenting (which is the whole point of significant whitespace).
> Deeply nested XML, provided the elements don't have some 300 character set of attributes all jammed into the opening element, is vastly easier to read than YAML.
Not really. More often than not, tags are visual noise that make it harder to scan for the actual content.
I have to read a lot of deeply nested XML for part of my job, and I wrote a parser to display it as YAML precisely because it's more readable. If your data is so convoluted that you need xml tags to make sense of it, that's usually a sign you need to either refactor it, or provide a proper display tool.
Way back in like 2012-2013 I was putting together workflows in ESRI ArcGIS.
The options for scripting were either VBScript or Python. Python was the better choice (AFAIR the UI would show what you were doing in it as python, which made it easy to take a manual flow you developed and automate.)
However, the editor window for scripts in the UI, used the default windows dialog font configured for the user. [0] I wound up having to put together a workflow where I'd have to copy-paste back and forth from a text editor, which was fairly unproductive.
[0] - No, changing the dialog font to fixed width was not a great solution, because then other apps suddenly had terrible UX due to their design....
Some context, this was launched at IndiaFOSS[0] yesterday
25 minute talk at https://www.youtube.com/live/AUrPdOZNsX8?feature=shared&t=13... (starts 3h:52)
The talk proposal is at https://fossunited.org/c/indiafoss/2025/cfp/arsnhack6n
And it primarily tries to avoid YAML horrors : https://noyaml.com/ and https://ruudvanasseldonk.com/2023/01/11/the-yaml-document-fr....
[0]: https://fossunited.org/indiafoss/2025
JSON5 allows comments.
Can someone explain to me what is so horrible about curly braces that we need a whole host of "human-friendly" configuration languages with nontrivial parsing just to get around them?
We are stuck in the old paradigm of characters taking space on the screen and the idea that a markup language must support classic dumb TUI. If, just imagine it, we used some Unicode range for control characters for the semantic markup and standardized UX for it, we wouldn’t need using normal characters as delimiters and escaping them in strings.
The following would have parseable structure, but would be free of visual noise.
People have suggested using the control characters for CSV structured files. The problem is that they are impossible to edit.
Control characters are invisible, using them means changing text editors to display them. They are also, outside the usual ones, hard to type. ASCII ones have Ctrl combos, but editors used those for other things.
Also, what is the difference between using some new character to start block and "{" or "\n"? Why have new thing to indicate new level when have space and tab?
Well in that case, it's all the ways that IDEs like to jank up whitespace, as well as the additional difficulty knowing 'context'.
With JSON it's fairly easy for me to know if I want to end my structure as well as the structure containing it, I can just type }}, and add the next element.
With whitespace you have to keep track of HOW MUCH whitespace, and trust me once you've got people who are entirely inconsistent with how much whitespace they use it becomes a huge PITA.
Don't ask me, I don't even know what was so bad about XML tags.
Probably the verbosity, necessity of a schema for typing, and mixing of text with tags as siblings.
I prefer curly braces. My editor has all sorts of comments to jump between opening and closing curly braces. This is not possible with whitespace.
Honestly, nothing. Except the endless debate on where the braces go, and how long they're allowed to stay on a single line.
It seems trivial, but replacing scope delimiters with a per-line signifier (i.e. indent) makes the scope of each line self-contained and sidesteps that discussion.
Is that worth YAYAML (Yet another YAML)? I don't know. But I certainly get the desire to skip the discussion :)
But it can't be minified without keeping the line endings and whitespace, unlike JSON.
You don't need to convince me. The question was "why would people want this", not "why are they wrong to want it" :)
The buttstock of a rifle, trigger and other operating details are "human oriented" and the muzzle end is also frequently "human oriented".
Not sure which one we have here.
I couldn't help but notice almost immediately one feature that is not human oriented, but most likely exists because it's easier for a machine to parse: single (":") vs double colon ("::"). This is not human-friendly. A human wants to write "key" "is" "value", and YAML has for a very long time supported a single ":" for "is" regardless of the actual type of the value.
I shouldn't have to care about what the type of the value is when writing out effectively YAML. This double-colon feature will do nothing but lead to bug reports from people confused as to why their document is invalid.
The comment above gives explanations defending subjective preferences about what "human oriented" means. That's fine as long as you remember that is what is happening: justification of subjective preferences. Other people can reasonably (or unreasonably) have different subjective preferences.
Also notice what the commenter above haven't done (yet, maybe they will?): done a full "forest level" comparison of all the trade-offs between the current HUML specification and ... what is your alternative proposal, exactly?
Based on my experience, I would guess that most people who design a language (and written a parser for it) for the first time will: (1) be surprised at how quickly design decisions snowball and lead to unexpected places; (ii) discover just how entangled design choices really are; (iii) will give up on trying to please everyone.
In my view, a language designer does really well to describe one's motivations, goals, tradeoffs, decisions, and then live with what you make, because... (a) making something real and useful is rad and (b) any language you make will probably have some weird stank you can't seem to get rid of.
The original designers of YAML explicitly declared in its name "Yet Another Markup Language" that it was designed to be a markup language, which it most certainly was not. Eventually somebody finally pointed out the mistake, and they sheepishly retronymed it "YAML Ain't Markup Language".
https://stackoverflow.com/questions/6968366/if-yaml-aint-mar...
On the other hand, and to your points, Relax/NG (both its XML and simplified syntaxes) is a beautiful successful example of wisely and collaboratively designing a new clean powerful system with the deep understanding of what a markup language really is (James Clark was deeply involved with many SGML and XML standards and implementations), and full cognizance of the strengths and weaknesses of other systems you're trying to replace (SGML DTDs, XML Schemas, TREX, RELAX, XDuce, and other experimental XML schema languages).
https://en.wikipedia.org/wiki/RELAX_NG
>In computing, RELAX NG (REgular LAnguage for XML Next Generation) is a schema language for XML—a RELAX NG schema specifies a pattern for the structure and content of an XML document. A RELAX NG schema is itself an XML document but RELAX NG also offers a popular compact, non-XML syntax.[1] Compared to other XML schema languages RELAX NG is considered relatively simple.
RELAX NG Compact Syntax
https://www.oasis-open.org/committees/relax-ng/compact-20021...
https://relaxng.org/jclark/design.html
The Design of RELAX NG
James Clark (jjc@thaiopensource.com)
Abstract: RELAX NG is a new schema language for XML. This paper discusses various aspects of the design of RELAX NG including the treatment of attributes, datatyping, mixed content, unordered content namespaces, cross-references and modularity. [...]
>Composability
>RELAX NG is designed to be highly composable. A schema language (or indeed a programming language) provides a number of atomic objects and a number of methods of composition. The methods of composition can be used to combine atomic objects into compound objects which can in turn be composed into further compound objects. The composability of the language is the degree to which the various methods of composition can be applied uniformly to all the various objects of the language, both atomic and compound. For example, RELAX NG provides a choice element that can be applied uniformly to elements, attributes, datatypes and enumerated values. This is not mere syntactic overloading. The choice element has a single uniform semantic in all these cases and can have a single implementation. Another example is the grammar element, which is the container for definitions. The grammar element is just another pattern and can be composed in just the same way as other patterns. Composability improves ease of learning and ease of use. Composability also tends to improve the ratio between complexity and power: for a given amount of complexity, a more composable language will be more powerful than a less composable one. [...]
>XML syntax
RELAX NG uses XML instance syntax to express schemas. Although this makes for a rather verbose schema language, it has some major advantages. Since a user of an XML schema language must necessarily already learn XML instance syntax, using XML instance syntax for the schema language reduces the learning burden on a schema user. It also allows XML tools and technologies to be applied to the schema. For example, a schema can be used to specify the syntax of the schema language. Another important benefit of XML syntax is extensibility. RELAX NG has an open syntax that allows the RELAX NG defined elements and attributes to be annotated with elements and attributes from other namespaces. RELAX NG DTD Compatibility [12] uses this annotation mechanism to extend RELAX NG with a mechanism for declaring default values for attributes. RelaxNGCC [23] uses this annotation mechanism to allow users to embed Java code in RELAX NG schemas, which gets executed as an XML document is parsed against the schema. An unofficial non-XML syntax for RELAX NG has also been developed [8]. The non-XML syntax can be used for authoring RELAX NG schemas by hand and can then be transformed into the standard RELAX NG XML syntax for interchange. [...]
I find this very human-friendly: "[double colon] permits vectors to be defined inline without additional syntax such as [ ... ] or { ... }."
(One could question how human friendly it is to call lists and dicts "vectors" though...)
https://huml.io/specifications/v0-1-0/#why
It's especially clear in the "inline dict" example. I really like it!
But that's not done for human readability, that's done for machine parsing? A human would understand just as well:
My mind has a feeling that this might be possible interpretation:
(Even if not legal, to be sure, I must backtrack and concentrate on this particular piece)There are many different humans. I definitely like the idea to separate “:: vs :”.
For me, it’s clearer with a double colon. Not intuitive, but extremely easy to get used to. When I see the first colon introduce a list, I have to go out of my way to not see the other colons as introducing lists.
I think we should have a name for the often undue examination and analysis of colon/semicolon usage in machine languages. I volunteer the name "colonoscopy."
And the obsession with inserting colons into things (and vice-verse) should be called "colonialism".
The double-colon is probably a necessity to disambiguate a scalar from an inline list that only has one scalar.
For example `x: 3` would be equivalent to `"x": 3` in JSON, but `x:: 3` is equivalent to `"x": [3]`
Maybe author of huml will read: I would prefer mandatory braces for inline stuff. “X:: 3” feels like a trick question.
A trailing comma would also solve this, but is equally awkward. A clear list delimiter would work for both machines and humans.
I found that example to be humerous, but specifically compared to the goals:
> Provide as few ways as possible—preferably one—of representing something.
Very Pythonic. Especially since representing a dict already has 2 ways, on the first page!
> Especially since representing a dict already has 2 ways,
And lists.
> Pythonic
Pythonic in the way that Python's 'There should be one...' is expressed through the existence of tuples, named tuples, dataclasses, regular classes and attrs (not part of the standard library but it seems to be as much of a goto as requests is)? ;)
Maybe the plural of "is" is "are" :)
But why double the character instead of picking another one... plenty of other non-alphanumeric characters to chose from.
There would at least be some ambiguity with single-value lists otherwise:
If
was a list, what would be?You could have it like in Python tuples where 1 is a scalar and 1, is a tuple.
True, but I think that wouldn't be any more intuitive or error safe than the :: syntax.
Language design often involves subjective tradeoffs. The author gives their rationale here: https://huml.io/specifications/v0-1-0/#why
Slightly off-topic, but I find the text of that anchor fragment amusing ("why? just why?") and a little disappointing. Automatic CMSs have robbed us of attention to detail - that anchor (for "Why `::`?") should probably be changed to `why-double-colon`.
The clear distinction between scalars and vectors appears to be the main advancement HUML offers.
I think it’s a neat improvement.
If the goal is to look similar to YAML and fix its problems and assert itself as something that's needed in a world with YAML, the introduction should probably explicitly call out some clear differences.
`::` is quite strange. 1) It only allows to resolve nesting conflicts for a single level. 2) Could be hard to read and could lead to reasoning mistakes. 3) Looks like an attempt to differentiate HUML from YAML somehow.
> Provide as few ways as possible—preferably one—of representing something.
TRUTH!
Or, expressed in YAML 1.1 [1]
As expressed in YAML 1.2 [2]:My only pet peeve: can we define decimals as dec128 rather then float64 in configuration files?
Strictly 2 spaces for indentation? What's human about that.
It's like YAML and MD had a baby
For something like this I would love to see a formal spec to go along with the examples.
I do appreciate that they lead with the examples. They convey 90% of the important information. TBH, having worked with yaml just enough to get by with k8s deployments, I could immediately spot how this would be an improvement.
Yeah, I don't disagree. I'd go further and say the examples are on-point for a "human oriented" language. But the formal spec reveals how simple or complicated this language is. (And I'm also writing this from the perspective of someone who uses a programming language that does not have a HOML implementation).
I like the idea of using `::` to denote a vector value.
"Human readability and editability above all else" would not chose significant whitespace for a markup language. IMO.
Or restrictions like "only one space allowed after : before a value"
On the contrary, such strictness makes it easy to lint / auto-format HUML.
That's for computers, though, not humans.
ctrl+f grammar
Term not found.
Me like teh grammarz 2. Plays 4 author someday could put at https://github.com/huml-lang then it slay
Wasn't this solved by yaml 1.2?
Reminder: you can use indentation to encode s-expressions. The result is very easy to parse and easy to read provided the underlying data structures are not insane.
https://srfi.schemers.org/srfi-49/srfi-49.html
Oh good, another even more confusing YAML alternative that still offers less functionality, flexibility and readability than JSON.
Data only for JSON, it lacks just like everything else as a configuration language. Arguments against I have seen are too verbose, too strict, and no comments. I am sure there are more.
It's not more verbose than this markup; strictness is only necessary for disambiguation; and comments are part of JSON5.
You could say the same thing about JSON compared to XML.
yeah, the 15th standard.. https://xkcd.com/927/ :)
XKCD predicting the future so well! :)
I was googling for the repo, and it looks like this project has a name collision with an 11-year-old, 3-star repo: https://github.com/shelling/huml
Oh lord. We already have TOML, which is an improvement on limited JSON when a human-readable, easily-diffable, more flexible format is needed.
We don't even need HCL (offers little value), YAML (has too many features making it inherently less secure), XML (is a mess with too many features and too much verbosity), or INI (insufficient features) except for existing and historical reasons.
In cases where a single file is attempted to be managed by multiple, competing interests, it's probably better to split the file into multiple, modular/include files like *.d/* so there would be less chances for merge conflicts.
And then there's /{proc,sys}-like configuration with one "value" per file where the path forms the heirarchy.
Please. Just. Stop reinventing wheels that were already round enough.
Off topic: Hard part of the wheel was not the round shape, but the axle. (That part actually was improved great many times)
This is the main reason why YAML and Python are bad. Give us CLEAR beginnings and ends to code statements and blocks, not these dubious beginnings and ends. Ignore white space and use clear EOL delineation. Clearly, XML and JSON are superior to YAML and even this weird-looking HUML. Not to mention almost any other language syntax being superior to Python.
I think it's a preference? I find both Python and YAML to give clear beginnings and ends using whitespace, and you can also see it visually.
There are plenty of times in Python and YAML I cannot visually figure out where some block ends.
JSON prevents this by explicitly closing lists and dicts. Though you do end up with Ladders to Heaven of `}`'s and `]`'s where you have no goddamn clue what is actually being closed out.
XML prevents this by explictly stating what element was just closed. Deeply nested XML, provided the elements don't have some 300 character set of attributes all jammed into the opening element, is vastly easier to read than YAML.
> There are plenty of times in Python and YAML I cannot visually figure out where some block ends.
To match the start of a Python block (with possibly other blocks nested within it) to its end: start at the (non-whitespace) column where the opening line begins, and go straight down until you find another line that starts in that column (or EOF).
Or you use an editor (or plugin) that just knows how to do this, just as you would with the balanced brackets. cf. https://vi.stackexchange.com/questions/7262 .
You can also just... not nest so deeply, or write so long. My functions rarely have more than ten lines are are usually not even inside classes; and I don't generally need more than three levels of indentation (that gets you, for example, a test within a loop within a function — which might well be better done with a comprehension anyway).
> XML prevents this by explictly stating what element was just closed.
Only for elements that cannot, even indirectly, contain other elements of the same element name. And for this limited safeguard, you double up every element name even in cases where it would otherwise be completely clear (which contributes to visual noise as the sibling comment points out). Of course, XML is designed for things that inherently need to be deeply nested. Your code usually doesn't.
https://en.wikipedia.org/wiki/Turing_(programming_language) tried the same idea. It didn't catch on.
> There are plenty of times in Python and YAML I cannot visually figure out where some block ends.
I might understand this objection for YAML, but for python, it's very clear: a block ends whenever the content on the next line is indented by four fewer spaces. (And lists and dicts are explicitly closed with brackets)
If you're talking about matching block starts to ends, then that's just as bad in json, if not worse; without an editor that does brace coloring, it's almost impossible to eyeball which brace goes to which block without indenting (which is the whole point of significant whitespace).
> Deeply nested XML, provided the elements don't have some 300 character set of attributes all jammed into the opening element, is vastly easier to read than YAML.
Not really. More often than not, tags are visual noise that make it harder to scan for the actual content.
I have to read a lot of deeply nested XML for part of my job, and I wrote a parser to display it as YAML precisely because it's more readable. If your data is so convoluted that you need xml tags to make sense of it, that's usually a sign you need to either refactor it, or provide a proper display tool.
That has never been a problem with Python, ever.
Story time!
Way back in like 2012-2013 I was putting together workflows in ESRI ArcGIS.
The options for scripting were either VBScript or Python. Python was the better choice (AFAIR the UI would show what you were doing in it as python, which made it easy to take a manual flow you developed and automate.)
However, the editor window for scripts in the UI, used the default windows dialog font configured for the user. [0] I wound up having to put together a workflow where I'd have to copy-paste back and forth from a text editor, which was fairly unproductive.
[0] - No, changing the dialog font to fixed width was not a great solution, because then other apps suddenly had terrible UX due to their design....
Posting a link to the XKCD comic would be a cliche at this point, yes?
Why not just use YAML?
Because of the reasons presented in the actual article that was posted by op...