Re: [Haskell-cafe] Parser left recursion

* Martin Drautzburg [2013-02-20 08:13:16+0100]

I do know for sure, that it is possible to parse "(1+2)+3" (ghci does it just fine). But I seem to be missing a trick.

Can anyone shed some light on this?

The trick in this case is that ghci doesn't use a recursive descent parser — it uses an LR parser (generated by Happy). Another workaround is to use memoization of some sort — see e.g. GLL ("Generalized LL") parsing. Roman