That is what he said though. I understand it is one example for a larger point, but it is an example that doesn't support that point at all. It is pretty hard to judge the overall point when the example is nonsense.
Your goal is to write a whole programming language.
Calculating where each statement starts and ends in order to serve a good error message is misdirected effort. Just use a terminating character, and use the standard one: a semi-colon.
Significant whitespace is popular as well. You can argue all day about it, but at the moment I think making a language "look like python" is the safer bet for a new language.
Why Python? Clojure and Elixir are two new languages with growing communities and they look nothing like Python.
His argument is essentially against something like Lisp or Forth where you have such a paucity of syntax that many erroneously written statements are syntactically valid and make it to runtime.
But the middle ground are languages that can detect a syntax error, but can't figure out exactly what it is. You don't get an error message saying "You should have a semi-colon here, want me to insert one?" Instead you get some vague message like "didn't expect this keyword here" a few lines after the missing semi-colon.
For the language I'm working on, I had started with significant whitespace. Then I realized that it would be a pain for things like anonymous callbacks (the kind of thing JS code is littered with) and that it was distracting. At least when you start, don't get hung up on the syntax, focus on basic things. What's important is what you are going to do with your AST, the lexer/parser part are the least important areas, unless you are doing a "syntactic skin" over a language (eg, coffeescript). You can always change the syntax later.
my_func_with_callbacks(arg1, def(x):
foo()
bar(),
5)
setTimeout ->
doSomething()
doSomethingElse()
, 1000
How?
And if we mean "significant whitespace" as in "newlines can act as statement and expression terminators" (since we were discussing semicolons as the alternative) we can also add a ton of other languages, like Ruby, JavaScript, Go, Scala, Visual Basic and Lua.
I agree with newlines vs semicolons (though I've always been told to write Javascript with semi-colons, and that's how I have encountered it in the wild).
I take your point about Haml, though Sass is actually Turing-complete, so I almost feel like it belongs in the list despite being really off-the-wall.
And I was only choosing from reasonably popular languages (so things like Boo are out even though they'd help my numbers). There just aren't that many mainstream programming languages out there. Four in a category seems like a pretty fair number to me. You could just as easily say functional programming isn't a thing if four mainstream languages is considered a paltry showing.
But it's optional in Haskell's case.
"The principles are rarely orthogonal and frequently conflict."
Producing genuinely useful error messages at all requires a complex parser, IMHO. It's not computationally obvious to look at a line of code and say 'actually you just missed this one character'. Requiring a terminating character gives you at least a sanity check starting point to work with - it alone will catch whole categories of errors.