[MichaelMoser123]

In yacc the generator will tell you about shift reduce conflicts. Once you have debugged the grammar the parser is likely to work. With parser combinators you have no such assurance - you don't know if your grammar has loops, the parser might get stuck easily while parsing. However for a simple and regular input language like sexpr everything is fine.

[sklogic]

In recursive descent you simply do not have any shift/reduce conflicts.

[MichaelMoser123]

you can have left recursion, or implicit left recursion in your recursive descent grammar, if you have then the parser gets stuck while parsing a clause that contains left recursion.

[sklogic]

Firstly, this have nothing to do with shift/reduce. Secondly, you can safely handle left-recursive grammars in Packrat (which, in turn, can be implemented with combinators).

[MichaelMoser123]

I didn't say that left recursion has anything to do with shift reduce conflicts. Please read again.

[sklogic]

I see, yes, you mentioned loops earlier. Anyway, it is not a problem for combinator-based parsing, just use Packrat with a left-recursive extension [1]

[1] http://www.vpri.org/pdf/tr2007002_packrat.pdf