Editing Primitive recursive function (section)

=== Additional primitive recursive forms ===

Some additional forms of recursion also define functions that are in fact
primitive recursive.  Definitions in these forms may be easier to find or
more natural for reading or writing. [[Course-of-values recursion]] defines primitive recursive functions. Some forms of [[mutual recursion]] also define primitive recursive functions.

The functions that can be programmed in the [[LOOP (programming language)|LOOP programming language]] are exactly the primitive recursive functions. This gives a different characterization of the power of these functions. The main limitation of the LOOP language, compared to a [[Turing-complete language]], is that in the LOOP language the number of times that each loop will run is specified before the loop begins to run.