Developed as an extension of Lisa Pascal, which in turn harked back to the UCSD Pascal model originally implemented on the Apple II, the language was strongly influenced by the Xerox Palo Alto Research Center (PARC) release of Smalltalk-80, v1 (which had been formerly ported to the Lisa), and by Modula.
According to Larry Tesler, Clascal was developed as a replacement for Apple's version of Smalltalk, which was "too slow" and because the experience offered by the Smalltalk syntax was too unfamiliar for most people.
[4] With the demise of the Lisa in 1986, Pascal and Object Pascal continued to be used in the Macintosh Programmer's Workshop for systems and application development[5] for several more years, until it was finally supplanted by the languages C and C++.
The MacApp application framework was based on Toolkit originally written in Clascal.
[3] Object Pascal, in turn, served as the basis for Borland's Delphi.