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Does your DSL little language need operator precedence?

19 points by ingve

by vrighter

0 subcomment

You can ignore precedence in the grammar, and then use a pratt parser or shunting yard or something to parse the precedence.
But yes, it does need it, usually. And it's not a huge thing to implement. I usually implement it in the grammar, with inline node folding inserted for left associative operators, which gets me a very nice clean AST.

by bitwize

1 subcomments

by fjfaase

0 subcomment

Just a single function per level is sufficient for implementing both right and left association. I do not see the problem.

by recursivedoubts

0 subcomment

hyperscript has some operator precedence, but within a given general precedence level you have to explicitly parenthesize if you use different operators:
https://github.com/bigskysoftware/_hyperscript/blob/06f9078a...
https://github.com/bigskysoftware/_hyperscript/blob/06f9078a...
this eliminates most practical precendence questions
NB: one thing that may strike people as strange is that the parse methods are on the parse elements themselves, I like to localize everything about a parse element in one place

by aappleby

1 subcomments

Yes, but it doesn't need any funny parsing trick to handle them. Just parse the whole statement as a list of expressions joined by operators, and then you can convert the flat list into a precedence-respecting tree with a few lines of code and an operator-to-precedence table.