If you have to learn just one programming language

[#ponce]

> For example the lambda syntax is terribly verbose in D compared to Scala 
> or Haskell.
> 

It may seem surprising to you, but there is a lot of project who can't afford using Scala or Haskell. 

If you're constrained to use D at your dayjob, imagine what could be to be forced to use C++. Wonderful hours spent finding that your destructor failed because it called virtual functions, while your stack trace magically disappear and you have to wait recompilation for 10 min.