Incomprehensible compiler errors

[Stuart]

On Tuesday, 31 July 2012 at 04:15:40 UTC, Bernard Helyer wrote:
> If they won't learn the compilation model, they won't be good 
> programmers.
> I'm not saying that good messages are a bad thing, but if they 
> don't
> understand the basic concept of source -> object file -> linker 
> -> exe or dll,
> then they will have a very hard time with D, pretty error 
> messages
> or no.

I understand the basic concept. What I didn't understand was why
omitting the optional keyword "module" caused linker errors; nor
did I understand why I couldn't use DFL after installing it
normally. It wasn't obvious that the DFL compilation had failed,
because the installer said "success!"