Ada originally followed BCPL and Pascal in distinguishing between commands (statements) and expressions, compared say to Algol68 which was an expression language. BCPL had VALOF/RESULTIS to link the two realms. It also had a conditional expression (A -> B, C) with the same meaning as B's and C's later (A? B: C) [which is probably better syntax]. Neither Pascal nor Ada had conditional expressions, for different reasons.
Ada has since added both "if" and "case" as conditional expression forms (including "elseif"). There's a discussion in the 2012 Rationale: http://www.ada-auth.org/standards/12rat/html/Rat12-3-2.html A big reason for introducing them was to support writing preconditions and postconditions. there are quantifying expressions as well (ie, "for all", "for some"). Originally, they were special pragmas in the SPARK subset but were finally promoted to be part of the language. Following the discussion above, I'd note though that one difference between (say) if a > b { m = a } else { m = b } and m := b if a > b { m = a } is that the former emphasises that the two cases (assignments) are mutually exclusive (m is either a or it is b), as opposed to (m is b unless it then becomes a), not very interesting here but there can be more complex cases. In converting a C# program to Go I've had a few instances where converting to if/else was clumsier or even more obscure, often it seems in constructors converted to struct literals, but in practice it's a minor point. As someone observed, sometimes little helper functions restore the flow and improve clarity (count!=0? total/count: 0) => avg(total, count) -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
