Editing Carbon (API) (section)

===Classic Mac OS programming===
The [[Classic Mac OS|original Mac OS]] used [[Pascal (programming language)|Pascal]] as its primary development platform, and the APIs were heavily based on Pascal's [[call semantics]]. Much of the [[Macintosh Toolbox]] consisted of [[subroutine|procedure calls]], passing information back and forth between the API and program using a variety of [[data structure]]s based on Pascal's [[variant record]] concept.

Over time, a number of [[object library|object libraries]] evolved on the Mac, notably the [[Object Pascal]] library [[MacApp]] and the [[THINK C]] Think Class Library, and later versions of MacApp and [[CodeWarrior]]'s PowerPlant in [[C++]].