On 20/08/2012, at 4:30 PM, Dobes Vandermeer wrote: > > There's a kind of program transformation called "static single assignment" > (SSA) that views each assignment to a local variable (var) as a new name.
Indeed. Felix does that. I previously described it, in terms of unravelling and re-ravelling. SSA is just a decomposition. It's often used to ready code for control or data flow analysis. Control analysis is simpler, but with closures it can still be very tricky! Data flow analysis of any kind is very hard. I'd love to have a data flow analysis in Felix. It would improve the optimiser out of sight. At present Felix only uses local pattern matching and a couple of global scans. You're getting confused about evaluation. C does eager evaluation of arguments. Haskell does lazy. Felix does either lazy, eager, or unspecified. The default is unspecified. SSA form you're thinking of you're assuming assignments are eager and considering re-orderings that don't change "semantics". In other words you're *defining* semantics as eager. The point you're missing is that Felix doesn't. Neither does Haskell. The 3 mode evaluation strategy used in Felix is more flexible that any other programming language. you can force eager, you can force lazy, or you can leave it up to the compiler to choose whichever is faster. The default is to leave it up to the compiler. That means YOU are responsible for recognising when the default isn't what you want. That's a purely "concrete syntax" choice. You don't like it. You'd rather the default be determinate. It isn't for good reason: it rarely makes any difference unless you're writing very high level code, in which case you're smart enough to know you have to change the strategy. I got caught myself, several times. RF got caught. Mike Maui got caught. So far you (Dobes) know about it but haven't been, which makes you smarter than the rest of us :) -- john skaller skal...@users.sourceforge.net http://felix-lang.org ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Felix-language mailing list Felix-language@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/felix-language
