Editing Mesa (programming language) (section)

===Syntax===
Mesa has an "imperative" and "algebraic" [[syntax]], based on [[ALGOL (programming language)|ALGOL]] and [[Pascal (programming language)|Pascal]] rather than on BCPL or [[C (programming language)|C]]; for instance, [[block (programming)|compound command]]s are indicated by the {{Mono|BEGIN}} and {{Mono|END}} keywords rather than [[brace (punctuation)|brace]]s. In Mesa, all keywords are written in uppercase.<ref name="manual" />

Due to PARC's using the 1963 variant of [[ASCII]] rather than the more common 1967 variant, the Alto's character set included a left-pointing arrow (←) rather than an underscore. The result of this is that Alto programmers (including those using Mesa, Smalltalk etc.) conventionally used [[camelCase]] for compound identifiers, a practice which was incorporated in PARC's standard programming style. On the other hand, the availability of the left-pointing arrow allowed them to use it for the assignment operator, as it originally had been in ALGOL.

When the Mesa designers wanted to implement an exception facility, they hired a recent M.Sc. graduate{{who|date=October 2021}} from Colorado<!-- John B. Goodenough ? --> who had written his thesis on exception handling facilities in algorithmic languages.  This led to the richest exception facility for its time, with primitives {{Mono|SIGNAL}}, {{Mono|ERROR}}, {{Mono|ABORT}}, {{Mono|RETRY}}, {{Mono|CATCH}}, and {{Mono|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.