[citation needed] Mesa introduced several other innovations in language design and implementation, notably in the handling of software exceptions, thread synchronization, and incremental compilation.
This technique did not scale very well to large application images (several megabytes), and so the Pilot/Mesa world in later releases moved away from the world swap view when the micro-coded machines were phased out in favor of SPARC workstations and Intel PCs running a Mesa PrincOps emulator for the basic hardware instruction set.
An actual example of such a hack is the BWSMagnifier, which was written in 1988 and allowed people to magnify sections of the workstation screen as defined by a resizable window and a changeable magnification factor.
Trained Mesa programmers from Xerox were well versed in the fundamental of GUIs, networking, exceptions, and multi-threaded programming, almost a decade before they became standard tools of the trade.
[6] Due to its strict separation between interface and implementation, Mesa allows true incremental compilation and encourages architecture- and platform-independent programming.
[7] Mesa has an "imperative" and "algebraic" syntax, based on ALGOL and Pascal rather than on BCPL or C; for instance, compound commands are indicated by the BEGIN and END keywords rather than braces.
This led to the richest exception facility for its time, with primitives SIGNAL, ERROR, ABORT, RETRY, CATCH, and CONTINUE.
As the language did not have type-safe checks to verify full coverage for signal handling, uncaught exceptions were a common cause of bugs in released software.