# Recursion vs Combinators.

## John Carter — 2001-12-11 03:21:27

    I'm in deep thought mode about recursion vs combinators.

    The fact that you can elimanate recursion is a deeply fascinating thing in

    itself, but beyond that fascination why should one do it?

    ie. What does it give you?

    Is it easier to prove things about a recursionless program?

    A scan of Manfred's site again didn't reveal any obvious benefits, am I

    missing something?

    John Carter                             Phone : (64)(3) 358 6639

    Tait Electronics                        Fax   : (64)(3) 359 4632

    PO Box 1645 Christchurch                Email : john.carter@...

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## Louis Madon — 2001-12-11 21:56:58

    On Tuesday, December 11, 2001, at 01:21  PM, John Carter wrote:

     > I'm in deep thought mode about recursion vs combinators.

    >

    > The fact that you can elimanate recursion is a deeply fascinating thing

    > in

    > itself, but beyond that fascination why should one do it?

    >

    > ie. What does it give you?

    >

    > Is it easier to prove things about a recursionless program?

    >

    > A scan of Manfred's site again didn't reveal any obvious benefits, am I

    > missing something?

     I don't think Manfred discusses the pros and cons at all.  It is an

    interesting question though, I only have a _hunch_ that it would be

    better, but I don't think anyone has seriously programmed that way to

    know for sure.

    I prefer to avoid redundancy in language design and right now having

    both recursion combinators and recursive definitions in Joy does seem

    redundant.

    Until there's been more theoretical and practical experience with

    recursion combinators (especially with respect to mutual recursion) I

    don't think your question can be properly answered.

    In the meantime, my answer would be "Why not eliminate recursive

    definitions?"

    Louis.

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