Stream: compiler development

Topic: Indent insensitive parsing and disallowing some line breaks

Joshua Warner (Feb 13 2025 at 04:37):

There are a couple of interesting places where, with indent insensitive parsing, we need to disallow line breaks at that point in the expression.

For example, you can't put a line break after the function and before the parentheses. and you can't put a line break between the ? operator and it's right operand.

Some motivating examples:

# If we allowed this:
foo
     (1, 2) # user intends these to be args of a funtion

# ... then we'd have trouble with this:
y = 1 + x
(1, 2) # returning a tuple

# If we allowed this:
text = File.readUtf8!(path) ?
                    ErrorReadingConfig # user intend this to be a binary '?'

# ... then we'd have trouble with this:
text = File.readUtf8!(path)? # Unary '?' is intended
MyTag value = give_me_a_tagged_return_value(text)

Joshua Warner (Feb 13 2025 at 04:38):

I don't think these cases are particularly controversial, but they are a few interesting exceptions to the general rule that you can usually put in a line break where you need to.

Brendan Hansknecht (Feb 15 2025 at 16:42):

@Richard Feldman this is the link

Anthony Bullard (Feb 19 2025 at 23:07):

I am of the opinion that there needs to be NoSpaceOpenRound and NoSpaceOpQuestion tokens. Application requires NoSpaceOpenRound and Try suffix requires NoSpaceOpQuestion

Joshua Warner (Feb 19 2025 at 23:24):

That makes sense to me

Last updated: Jul 06 2025 at 12:14 UTC