APL was special among the early languages in that it had memory management, implicit types, highly optimized support for multidimensional array operations, and

APL was special among the early languages in that it had memory management, implicit types, highly optimized support for multidimensional array operations, and composable functions. It was the language for anything mathematical. The characterset was actually a plus: it allowed the experienced user to read it as one reads math, which in turn made experimentation and algorithm optimization extremely fast. The downsides of course being the technical debt at all levels of the stack: from the files filled with code which one is wise to not touch, to the characters which date back to the days of pressing backspace on a typewriter to combine multiple symbols, to the machinations necessary to roll out interpreted code to someone else's system... Well, since the rise of Matlab (and now Numpy) there are alternatives which fill APL's niche, but I do miss the elegance of everything being an array.