It's math-y. As in "let n be a natural, ...".

> I don't see any argument for it in a C-like language.

The inventor of the C-like languages B and NB (which then inspired C) agreed and used the more intuitive auto.

  {
    auto x = 1; /* x is implicitly an integer */
  }

Now it's back in vogue in the C-like language C++. It doesn't mean "automatic storage", though.

>It makes sense in "let x in {}" type expressions

Without jumps, all code can be rewritten to be a series of "let x = ... in <expression>"

The fact Java has statements instead of everything being expressions is a design flaw and should be rectified not glorified.

Er. Why do you think that?

It's essentially what SSA is.