I’ve released my simple fan control program described in this entry (see also part one).
THIS CODE MAY MELT YOUR CPU - download only if you plan to read it, test it, and/or hack on it. The license makes it clear that it comes with no warranty.
I’ve already received an interesting email from Mark M Hoffman in reply to my post to the mailing list announcing it, drawing my attention to PID control loops. Looks like it could be a worthy avenue of investigation. I’ve replied with a description of one issue I see with applying a PID controller in this domain.
June 28th, 2006
Paul Crowley
Today I googled for “code as data”. The first hit that came up was this, a tutorial on Groovy that cheerfully proclaims that what is meant by “code as data” is closures! No, no, NO!!!!
“Code as data”, aka “code is data” signifies the ability to manipulate
code, i.e. to construct and take apart programs. At the most primitive level that can be accomplished
by representing source code as strings, which is possible in most programming languages. Going beyond that, many
programming languages define an AST data structure, with a parser and
pretty printer, that allows manipulation of code in a more structured
manner, enforcing most, if not all, syntactic constraints of the
language.
However, neither of these approaches fully capture what is meant by
“code is data” in the Lisp tradition. There code really is
data. There is no special AST data type and associated parser and
pretty printer. Instead all programs are represented in terms of the
ordinary data types of the language, such as symbols and lists. The
concrete syntax of programs is subsumed by the standard external
representation of data.
None of this has anything to do with closures.
June 28th, 2006
matthias