condp syntax for Scheme.

condp.scm

(define-library (niyarin condp)
   (import (scheme base))
   (export condp condp-right)

   (begin

    (define-syntax condp-aux
         (syntax-rules (else left right)
            ((_ _ test (used ... ) (else expression ...) clauses ...)
               (cond  used ... (else expression ...)))

            ((_ _ test (used ...))
             (cond used ...))

            ((_ left (test1 test2 ...) (used ... ) (test-target expression ... ) clause2 ... )
               (condp-aux left (test1 test2 ...) (used ... ((test1 test-target test2 ... ) expression ... )) clause2 ... ))

            ((_ right (test  ...) (used ... ) (test-target expression ... ) clause2 ... )
               (condp-aux right (test ...) (used ... ((test ... test-target) expression ... )) clause2 ...))))

     (define-syntax condp 
         (syntax-rules (else)
            ((_ test cond-clause ... ) 
               (condp-aux left test () cond-clause ... ))))

     (define-syntax condp-right
         (syntax-rules (else)
            ((_ test cond-clause ...)
               (condp-aux right test () cond-clause ... ))))))