REXX - Features

Features

REXX has the following characteristics and features:

• simple syntax
• small instruction set containing just two dozen instructions
• freeform syntax
• case insensitive tokens, including variable names
• character string basis
• dynamic data typing, no declarations
• no reserved keywords, except in local context
• arbitrary numerical precision
• decimal arithmetic, floating-point
• a rich selection of built-in functions, especially string and word processing
• automatic storage management
• crash protection
• content addressable data structures
• associative arrays
• straightforward access to system commands and facilities
• simple error-handling, and built-in tracing and debugger
• few artificial limitations
• simplified I/O facilities
• unconventional operators
• only partly supports Unix style command line parameters, except specific implementations
• provides no basic terminal control as part of the language, except specific implementations
• provides no generic way to include functions and subroutines from external libraries, except specific implementations

REXX has just twenty-three, largely self-evident, instructions (e.g., call, parse, and select) with minimal punctuation and formatting requirements. It is essentially an almost free-form language with only one data-type, the character string; this philosophy means that all data are visible (symbolic) and debugging and tracing are simplified.

REXX syntax looks similar to PL/I, but has fewer notations; this makes it harder to parse (by program) but easier to use, except for cases where PL/I habits may lead to surprises.