Hi Jeffrey, On Mon, Sep 28, 2015 at 8:28 PM, Jeffrey Brown wrote:

I imagine a parser that operates on (String,[String]) pairs, for which the second element allows the user to define precedence on the fly.

For instance, it would read the pair (x,y) = ("a , b : c", [":" , ","]) as "(a , (b : c))" because y informs the parser that in x the colon binds first, then the comma.

I know it is possible, because Haskell does it already! In Haskell we can define novel infix operators on the fly, including their precedence relative to each other.

I don't know how, though, so that's my question.

You might like to look at Text.Parsec.Token[1], which does exactly what you describe. [1] https://hackage.haskell.org/package/parsec-3.1.9/docs/Text-Parsec-Expr.html

-- Jeffrey Benjamin Brown

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I know it is possible, because Haskell does it already! In Haskell we can define novel infix operators on the fly, including their precedence relative to each other. I don't know how, though, so that's my question.

You might like to look at https://en.wikipedia.org/wiki/Operator-precedence_grammar Stefan