Mal – Make a Lisp, in 68 languages

Re:Mal – Make a Lisp, in 68 languages by spc476 on Tuesday September 12, 2017 @06:32PM (#15233557)

I'll use x86-32 for elaboration [1]. When the CPU sees the byte sequence 0xB8 0x90 0x41 0x5A 0x7B, it has to interpet what those bytes mean. It sees the 0xB8, so then it knows that you are loading the EAX register with an immedate value. The next four bytes (0x90, 0x41, 0x5A, 0x7B) are read and stored into EAX (as 0x7B5A4190, because Intel is little endian).

That is the case for all instructions. Each one is interpreted by the CPU. And for modern CPUs, even translated into an internal format that is futher interpreted.

[1] Sans power right now. Using my cellphone as a hot-spot and my iPad as a laptop. The aftermath of hurricanes is brutal in Florida.

[ Parent | on HN ]

Re:Mal – Make a Lisp, in 68 languages by omginternets on Wednesday September 13, 2017 @04:31AM (#15236496)

Gotcha, but then (unless I'm misunderstanding) one of these interpreters is not like the other. Namely, assembly 'interpretation' happens on bare metal. Were you previously suggesting that understanding a lisp interpreter will help in understanding CPU architecture?

(Good luck recovering from the hurricane! Keep your head down!)

[ Parent | on HN ]

Re:Mal – Make a Lisp, in 68 languages by spc476 on Wednesday September 13, 2017 @05:56PM (#15243097)

I was replying more to jospar's post about learning what an 'if' was, what a 'boolean' was, etc. What's an 'if'? Ultimately it's a comparison of two numbers and a transfer of control based upon said comparison. Some architectures that's one instruction, some two.

[ Parent | on HN ]