[Prikrutil]

Some people have already mentioned that learning a new language often makes you a better programmer in other ones. I don't have any experience in improving skills that way (I started learning Haskell, but it's too early to see whether it's making my Erlang better or not), but what I've learned is that unwillingness to learn new languages makes you a fanboy of language(s) you already know. Being a fanboy of any language is what I'm actually afraid of (just because I know what it is to be a fanboy =)

Suppose, there is a guy (I will name him "Poluekt"), who is a master of Foo language (sounds like "a master of kung-Foo!"). Foo is a really good functional language having active community, excellent runtime and good libraries; Poluekt is good at writing in Foo but isn't brave enough to say "I'm not a Foo, I'm a programmer who wants to choose between languages when it comes to solving non-trivial problems".

What will happen with such a guy when he hear of nice features a new language (say, Bar) offers to solve problems in domain where Foo is (was?) the language of choice? Oh, it will be very offensive for our guy to hear that Bar beats Foo in some cases or even is press it. It will make Poluekt so unhappy, irritable...

Nobody knows how many Bars there will be on the Poluekt's way, but learning them seems a good way to become a good specialist.