created: 20150105133800000
modified: 20150105134300000
title: RailroadDiagrams

Railroad diagrams, sometimes called syntax diagrams, are a visual way of explaining the syntax rules of a computer language. Reading one is like reading a public transport map.

Each diagram starts on the left and ends on the right. Simply follow any line from the startpoint to the endpoint. All the alternative lines are equally valid. A line will sometimes jump over an item that is optional, or loop back to indicate that an item can be repeated.

<$railroad text="""
start [:optional] {repeated +","} end
"""/>

Characters in round boxes are literal, i.e. they denote themselves. A name in a rectangular box denotes a further railroad diagram.

The railroad diagrams on this site are generated using the [[Railroad Plugin]].