Editing Off-side rule (section)

{{Short description|Programming language syntax rule that defines code block demarcation via indentation}}
{{About|the programming language syntax feature||Offside (disambiguation)}}
{{Refimprove|date=December 2011}}
{{Use mdy dates|date=July 2022}}

The '''off-side rule''' describes [[Syntax (programming languages)|syntax]] of a [[computer]] [[programming language]] that defines the bounds of a [[block (programming)|code block]] via [[indent style|indentation]].<ref>
{{cite conference
| first= G.
| last= Hutton
| editor-first= Kei
| editor-last= Davis
| editor2-first= John
| editor2-last= Hughes
| title= Parsing Using Combinators
| book-title= Functional Programming: Proceedings of the 1989 Glasgow Workshop 21–23 August 1989, Fraserburgh, Scotland 
| pages= 362–364
| publisher= Springer Science & Business Media
| date= Dec 6, 2012
| isbn= 9781447131663
| url= https://books.google.com/books?id=GiLjBwAAQBAJ&dq=offside+rule+programming&pg=PA363
| access-date= September 3, 2015}}
</ref><ref>
{{cite conference
| first= D.A.
| last= Turner
| editor-first= Hans Wolfgang
| editor-last= Loidl
| editor2-first= Ricardo
| editor2-last= Peña
| title= Some History of Functional Programming Languages (Invited Talk)
| book-title= Trends in Functional Programming: 13th International Symposium, TFP 2012, St Andrews, UK, June 12–14, 2012, Revised Selected Papers
| pages= 8
| publisher= Springer
| date= August 13, 2013
| isbn= 9783642404474
| url= https://books.google.com/books?id=B_25BQAAQBAJ&dq=Offside+rule+programming&pg=PA8
| access-date= September 3, 2015}}</ref>

The term was coined by [[Peter Landin]], possibly as a pun on the [[Offside (association football)|offside law]] in [[association football]].

An off-side rule language is contrasted with a [[free-form language]] in which indentation has no syntactic meaning, and indentation is strictly a matter of [[Programming style|style]].

An off-side rule language is also described as having '''significant indentation'''.