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> In languages like Scala, Java, C#, and Swift, it basically never happens. Scalaz and cats use tail calls extensively and wouldn't be possible without them.

• kragen 4y ago
  How does that work on the JVM?
  • yw3410 4y ago
    Scala only does single method tail recursion and rewrites it into a while loop. Cats and other libraries use a technique called trampolining which basically moves the frames to the heap (or a mixed technique where they do recurse a certain depth on the stack before switching to trampolining).
    • kragen 4y ago
      That sounds like it means that Scala doesn't support general tail-call elimination, so people don't write mutually tail-recursive code, instead transforming things that would naturally be expressed that way into a different structure that Scala does support.
      • yw3410 4y ago
        Yes. It can be a major PITA, in certain problem spaces and I think most people don't pretend it's a great solution but ultimately accept it as a limitation of being hosted on the JVM.