I've been using Go a lot lately. It's difficult to overstate just how much simpler it makes writing highly-concurrent server-type programs. Entire classes of bugs, issues, and puzzles just vanish.
The biggest thing Go gives me is that it's really easy to manage code bases that grow organically - refactoring a project that grows from 50 LOC to 5000 LOC is almost painless in Go - no other language that I've seen has dealt with this aspect of code development so well.
Secondarily, gofmt makes code very standardized and easy to skim. It takes Python's 'only one (obvious) way to do it' one or two steps further, by forcing everyone to to write their code the same way. This makes refactoring a lot easier because you don't need to read as much code each time in order to understand what's going on (or at least, you can mentally parse it much faster).
Finally, the context-free grammar combined with a strong, static type system means that migrating code from an old (incompatible) version of Go to the most recent one can be done painlessly with the 'go fix' tool. This isn't your py2to3 tool - this accepts valid (old) Go code as input and reliably produces valid (up-to-date) Go code as the output.
That last bit isn't actually used in refactoring manually, but I make note of it because very few languages give you anything close to this level of reliability with code modification, which speaks volumes about the design of the language's grammar.
I don't want to use a language that doesn't come with a parser in the standard library anymore.
`gofmt -r 'InitialName -> FinalName'`
Very interesting to hear. Any chance you could expand on this a bit more?
The package system also enforces (at compile-time) that every imported package be used (and also that every named identifier be defined, which most dynamic/interpreted languages can't do). This applies not just to imported packages, mind you, but to any lvalue - if you declare/assign to an lvalue that's never used as an rvalue later, you can't compile the program.
That's really helpful when refactoring, because it makes it easy just to move a bunch of code between files, then follow the breadcrumb trail of compiler errors (not warnings!) to figure out what still needs to be fixed. The compiler won't tell you everything you need to do, but it's sort of like having a Roomba helping pick up after you while you clean your house manually.
Yes, for those genius programmers who never makes any mistakes, this may not be much of an improvement. But for those of us who don't trust our human brains as much and want to be absolutely sure that these silly errors don't slip through, it takes a huge load off the mind.
In C++ header dependencies are also a DAG, since include guards prevent cycles (and multiple includes). What makes Go faster are a few things: (1) C++ headers contain templates, which are slot to compile; (2) Go only looks at direct imports and uses the compiled form of those imports, rather than recursing over their imports (again); (3) Go is simpler to parse; and (4) there is no overloading, so symbol/method resolving is simpler.
I also think that the advantage is often overstated. C++ is a nightmare in this respect, C programs and libraries often compile very fast (on my current machines, running configure often takes much more time than the actual compilation), the same applies to e.g. Java code.
That's really helpful when refactoring,
And annoying for testing, the printf example has been beaten to death. (Yes, I know that you can add a line such as var use = fmt.Println).
But for those of us who don't trust our human brains as much and want to be absolutely sure that these silly errors don't slip through
It's always surprising how Go fans can sell a feature that any strong statically typed language always had (easy refactoring by letting the type system work) can sell as something unique and new ;).
If you are forward declaring a function, you are just promising that it is present during linking. So, during compilation it is not an edge in the graph.
If you are forward declaring a data type such as a class, a full definition needs to be visible at its first use or you are using the type as a pointer:
class A;
class B {
A *d_a;
[...]
};
Could you give an example where C++ dependencies are not a DAG during compilation?
I don't think this has much to do with compilation speed though.