Editing Parsing expression grammar (section)

=== No compilation required ===
Many parsing algorithms require a preprocessing step where the grammar is first compiled into an opaque executable form, often some sort of automaton. Parsing expressions can be executed directly (even if it is typically still advisable to transform the human-readable PEGs shown in this article into a more native format, such as [[Lisp (programming language)#Symbolic_expressions_(S-expressions)|S-expressions]], before evaluating them).