On Tue, May 7, 2013 at 3:14 PM, Don Green <infodeveloper...@gmail.com>wrote:
> Can you apply the verbage that must be represented by the symbols in > Racket regexp documentation shown below: > > ;;= means what? > > | means what? > > <pces> means what? > > Hi Don, You are seeing instances of Backus-Naur Form (BNF): http://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form This is not exclusive to Racket documentation. It is a syntax that is commonly used in computer science to express the structure of a language. ;;= means what? > > | means what? > > <pces> means what? > > When I read something like: ‹*regexp*› ::= ‹*pces*› Match ‹*pces*› | ‹*regexp*›|‹*regexp*› Match either ‹*regexp*›, try left first I read this as: "A regular expression regexp is either: * A "pces", which will be defined later in the document, OR * An inner regexp, followed by a pipe "|", followed by another regexp OR ... where ":==" is notation meant to distinguish the left and right hand sides of the definition, <X> is a reference to another piece of structure, and "|" is mean to denote one of a possible set of candidates.
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