I do not use cl-launch, but for some tasks at job I wanted to pipe programs, and just wanted to try implementing something myself. The with-pipeline macro creates temporary fifos to connect programs and threads (random example):

    (let ((counter 0))
      (with-pipeline ()
        (program "ls" "-1la")
        (lambda-line (line)
          (format t "~x~%" (incf counter (length line))))
        (program "sed" "-n" "s/A/_/g ; /__/ p"))
      counter)
         

Outputs and return:

    2__8
    15399

Macroexpansion:

   (catch :pipeline
     (block nil
       (let* ((#:input%2195 (pipeline::ensure-stream nil :input nil))
              (#:output%2196 (pipeline::ensure-stream t :output nil))
              (#:error%2197
               (pipeline::ensure-stream :output :error #:output%2196)))
         (let ((#:g2199 (program "ls" "-1la"))
               (#:g2200
                (lambda-line (line)
                  (format t "~x~%" (incf counter (length line)))))
               (#:g2201 (program "sed" "-n" "s/a/_/g ; /__/ p")))
           (pipeline.pipes:with-pipes% (#:pipes2198 2)
             (lastcar
              (mapcar #'pipeline.filters:clean
                      (list
                       (pipeline.filters:spawn #:g2199 :input #:input%2195 :output
                                               (pipeline.pipes:pipe-out
                                                (svref #:pipes2198 0))
                                               :error #:error%2197 :wait nil)
                       (pipeline.filters:spawn #:g2200 :input
                                               (pipeline.pipes:pipe-in
                                                (svref #:pipes2198 0))
                                               :output
                                               (pipeline.pipes:pipe-out
                                                (svref #:pipes2198 1))
                                               :error #:error%2197 :wait nil)
                       (pipeline.filters:spawn #:g2201 :input
                                               (pipeline.pipes:pipe-in
                                                (svref #:pipes2198 1))
                                               :output #:output%2196 :error
                                               #:error%2197 :wait t)))))))))

https://github.com/christophejunke/pipeline