Saying Good-bye: HARP

This begins a new series of blog posts that will continue over the next few months as we say "Good-bye!" to parts of Open Dylan.

Freedom comes when you learn to let go
Creation comes when you learn to say no

  -- Madonna, The Power of Good-Bye

We're beginning a process by which we'll start slimming down the compiler and the libraries, letting go of some major chunks of code, with the goal of improving the hackability of the compiler and enabling us to make new leaps in functionality.

What is HARP?

HARP is the Harlequin Abstract RISC Processor and was designed and developed at Harlequin in the late 1980s. It was used in Harlequin's LispWorks and later translated to Dylan for use in Harlequin's DylanWorks (which is now Open Dylan).

Clive Tong, an engineer at Harlequin in 1989, briefly described it as:

The compiler targeted an instruction set known as HARP (Harlequin Abstract RISC Processor), and then HARP instructions were translated into machine instructions using a template matching scheme. HARP had an infinite set of registers, and the register colouring happened as part of this templating processing.

Some additional details about the early design of HARP ...

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