Bliss was Re: DEC program listing

On 15/08/2005, at 9:11 PM, John Allain wrote: OK, from my viewpoint (based a lot on BLISS-10 but I've done BLISS-32 programming as well). Good features (IMHO) 1) No GOTO - probably the first systems programming language to be designed without one. 2) Generated good code - considerable emphasis was made to ensuring that BLISS-10 could be used to replace assembler. 3) Everything is an lvalue. BLISS uses the "." operator to get the contents of an lvalue. So what in most other languages would be written as i := i + 1 becomes i := .i + 1, unless of course you want to put the address of the location after i into it. This of course, led to lots of stupid programming errors, my favorite one (and one that lead to lots of interesting effects) was a bit of code that read something like WHILE work EQ 1 DO lots of code OD Of course, given that this code effectively said, while the address of work is 1 do "lots of code" lead to the optimizer eliminating lots of dead code and a very small executable :-) Everything as an lvalue works backwards to the way c does it and allows you to do really neat stuff with indirect addressing. It makes call by value and call by reference far more obvious. Combined with user defined structures (see point 4) this allows very elegant structure manipulations. 4) User defined structures. You can set up a structure to define data structures. This is very analogous to c struc. 5) Modules. BLISS was designed from day one to support modules and all the necessary things to allow them to be linked against each other. 6) Co-routines were part of the language. Of course, I don't think I ever used this but it's there. 7) Macro processing is built in, not an add-on. Huw Davies | e-mail: Huw.Davies at kerberos.davies.net.au Melbourne | "If soccer was meant to be played in the Australia | air, the sky would be painted green"