(defun main []
    (let [[sourceDir numPages] (Sys.args)]
        (.then
            (Promise.all
                (for file (Fs.readdirSync sourceDir)
                    (PDFDocument.load (Fs.readFileSync (+ sourceDir "/" file)))))
            (lambda [inputPdfs]
                // TODO make an awaitLet macro that .thens a promise or all() of promises into a binding
                (.then (PDFDocument.create) (lambda [saladPdf]
                    (.then 
                        (Promise.all
                            (for _ #|0... Std.parseInt(numPages)|# 
                                (let [:PDFDocument pdf (nth inputPdfs (Std.random inputPdfs.length))
                                        page (Std.random (pdf.getPageCount))]
                                    (saladPdf.copyPages pdf [page]))))
                        (lambda [pages]
                            (doFor page pages (saladPdf.addPage (first page)))
                            (.then (saladPdf.save) (lambda [bytesOut]
                                (Fs.writeFileSync "out.pdf" bytesOut)))))))))))