When people say that in their experience all programming languages
are basically equivalent, they're making a statement not about
languages but about the kind of programming they've done.
99.5% of programming consists of gluing together calls to library
functions. All popular languages are equally good at this. So one
can easily spend one's whole career operating in the intersection
of popular programming languages.
But the other .5% of programming is disproportionately interesting.
If you want to learn what it consists of, the weirdness of weird
languages is a good clue to follow.
Weird languages aren't weird by accident. Not the good ones, at
least. The weirdness of the good ones usually implies the existence
of some form of programming that's not just the usual gluing together
of library calls.
A concrete example: Lisp macros. Lisp macros seem weird even to
many Lisp programmers. They're not only not in the intersection of
popular languages, but by their nature would be hard to implement
properly in a language without turning it into a dialect of
Lisp. And macros are definitely evidence of techniques that go
beyond glue programming. For example, solving problems by first
writing a language for problems of that type, and then writing
your specific application in it. Nor is this all you can do with
macros; it's just one region in a space of program-manipulating
techniques that even now is far from fully explored.
So if you want to expand your concept of what programming can be,
one way to do it is by learning weird languages. Pick a language
that most programmers consider weird but whose median user is smart,
and then focus on the differences between this language and the
intersection of popular languages. What can you say in this language
that would be impossibly inconvenient to say in others? In the
process of learning how to say things you couldn't previously say,
you'll probably be learning how to think things you couldn't
Thanks to Trevor Blackwell, Patrick Collison, Daniel Gackle, Amjad
Masad, and Robert Morris for reading drafts of this.