Intuiting Pratt Parsing
by signa11 on 3/30/2026, 12:31:52 PM
https://louis.co.nz/2026/03/26/pratt-parsing.html
Comments
by: randomNumber7
I can recommend anyone reading pratts original paper. Its written in a very cool and badass style.<p><a href="https://dl.acm.org/doi/epdf/10.1145/512927.512931" rel="nofollow">https://dl.acm.org/doi/epdf/10.1145/512927.512931</a>
4/1/2026, 11:43:35 AM
by: logdahl
Love Pratt parsing! Not a compiler guy, but I've spent way too many hours reflecting on parsing. I remember trying to get though the dragon book so many times and reading all about formal grammar etc. Until I landed on; recursive descent parsing + Pratt for expressions. Super simple technique, and for me is sufficient. I'm sure it doesn't cover all cases, but just for toy languages it feels like we can usually do everything with 2-token lookahead.<p>Not to step on anyone's toes, I just don't feel that formal grammar theory is that important in practice. :^)
4/1/2026, 10:58:26 AM
by: priceishere
An even simpler way imo, is explicit functions instead of a precedence table, then the code pretty much has the same structure as EBNF.<p>Need to parse * before +? Begin at add, have it call parse_mul for its left and right sides, and so on.<p><pre><code> parse_mul() { left = parse_literal() while(is_mul_token()) { // left associative right = parse_literal() make_mul_node(left, right) } } parse_add() { left = parse_mul() while(is_add_token()) { // left associative right = parse_mul() make_add_node(left, right) } } </code></pre> Then just add more functions as you climb up the precedence levels.
4/1/2026, 11:24:38 AM