It's pseudocode. A mix of Python's block structure, C's style of variable introduction, and Pascal's use of ":=" for assignment and "=" for equality. Oh, and assigning to output variables instead of explicit return is from Go, although the tradition is much older, of course.
As for using "'" in variable names, can't recall from the top of my head what language it's from (I don't think it's Lisp), but something does that.
Nice, that's what i noticed; I rather like its clean structure.
But since it was put together by you/not-you, does it have a name and is it used as a Specification/IR/DSL language somewhere (since you gave the algorithm in it) ?
As for using "'" in variable names, can't recall from the top of my head what language it's from (I don't think it's Lisp), but something does that.