Pastel (programming language)

Pastel is an extended version of the Pascal programming language, created in 1982 for Amber, an operating system for the S-1 supercomputer project at Lawrence Livermore National Laboratory in California.^[1] The Pastel compiler was the inspiration for Richard Stallman's GNU C compiler.^[2]

Pastel was conceived by Jeffrey M. Broughton, then Project Engineer in charge of compilers and operating system software for the S-1 project,^[3] because of dissatisfaction with the PL/1 language in which Amber was being implemented. The language was named Pastel ("an off-color Pascal").

Compared with Pascal compilers of that period, Pastel's features included:^[4]

• Improved type definition
• Parametric types
• Explicit packing and allocation control
• Additional parameter passing modes
• Additional control constructs
• Set iteration
• Loop-exit form
• Return statement
• Module definition
• Exception handling
• General enhancements
• Conditional Boolean operations
• Constant expressions
• Variable initialization