The GNU APL Bible

The GNU APL Bible: Implementing APL in C++

A complete tour of a working APL interpreter, from the first keystroke to the parallel execution of a reduction across eight cores. GNU APL is the only actively maintained implementation of ISO/IEC 13751 - APL with nested arrays - and this book reads its 21,000-file C++ source tree the way a language and its implementation deserve to be read together.

Twenty-nine chapters follow the interpreter end to end: the Value and Cell classes at the heart of the APL array model, the tokenizer and the SHIFT/REDUCE parser, the scalar-function and non-scalar-function machinery, operators, the state indicator and the REPL, memory management and workspace serialization ()SAVE and )LOAD), the sixty-plus system functions behind every quad-prefixed name, native functions and auxiliary processors, the DATIS-P parallel APL machine and GNU APL's own parallel execution model, WebSocket and GUI interfaces, and a guided tour of the source tree itself - down to a worked example of adding a brand-new system function from scratch.

Written by GNU APL's own author, with every code citation checked against the actual source and every example run through the real interpreter. For the C++ engineer who wants to see a complete, real interpreter built end to end - and for the APL programmer who has always wondered what happens after Enter is pressed.