awaitLet

kiss/src/kiss/Macros.hx

@@ -369,6 +369,41 @@ class Macros {
             return null;
         };
 
+        // TODO macros for ifLet, whenLet (for assign then truthy check), caseLet (for extracting from enums)
+
+        function awaitLet(wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) {
+            wholeExp.checkNumArgs(2, null, "(awaitLet [[promise bindings...]] [body...])");
+            var bindingList = switch (exps[0].def) {
+                case ListExp(bindingExps) if (bindingExps.length > 0 && bindingExps.length % 2 == 0):
+                    bindingExps;
+                default:
+                    throw CompileError.fromExp(exps[0], 'awaitLet bindings should be a list expression with an even number of sub expressions (at least 2)');
+            };
+            var firstName = bindingList.shift();
+            var firstValue = bindingList.shift();
+            return CallExp(FieldExp("then", firstValue).withPosOf(wholeExp), [
+                CallExp(Symbol("lambda").withPosOf(wholeExp), [
+                    ListExp([firstName]).withPosOf(wholeExp),
+                    if (bindingList.length == 0) {
+                        CallExp(Symbol("begin").withPosOf(wholeExp), exps.slice(1)).withPosOf(wholeExp);
+                    } else {
+                        awaitLet(wholeExp, [ListExp(bindingList).withPosOf(wholeExp)].concat(exps.slice(1)), k);
+                    }
+                ]).withPosOf(wholeExp),
+                // Handle rejections:
+                CallExp(Symbol("lambda").withPosOf(wholeExp), [
+                    ListExp([Symbol("reason").withPosOf(wholeExp)]).withPosOf(wholeExp),
+                    CallExp(Symbol("throw").withPosOf(wholeExp), [
+                        // TODO generalize CompileError to KissError which will also handle runtime errors
+                        // with the same source position format
+                        StrExp("rejected promise").withPosOf(wholeExp)
+                    ]).withPosOf(wholeExp)
+                ]).withPosOf(wholeExp)
+            ]).withPosOf(wholeExp);
+        }
+
+        macros["awaitLet"] = awaitLet;
+
         return macros;
     }
 

kiss/src/kiss/SpecialForms.hx

@@ -255,8 +255,6 @@ class SpecialForms {
             ESwitch(k.forCaseParsing().convert(args[0]), args.slice(1).map(Helpers.makeSwitchCase.bind(_, k)), defaultExpr).withMacroPosOf(wholeExp);
         };
 
-        // TODO macros for ifLet, expectLet, which extract from enums
-
         // Type check syntax:
         map["the"] = (wholeExp:ReaderExp, args:Array<ReaderExp>, k:KissState) -> {
             wholeExp.checkNumArgs(2, 2, '(the [type] [value])');

projects/pdf-salad/src/Main.hx

@@ -8,5 +8,7 @@ import kiss.Kiss;
 import kiss.Prelude;
 import Externs;
 
+using StringTools;
+
 @:build(kiss.Kiss.build("src/Main.kiss"))
 class Main {}

projects/pdf-salad/src/Main.kiss

@@ -1,28 +1,25 @@
-(defun loadAll [paths :Function callback &opt :Array<PDFDocument> pdfs]
+(defun loadAll [:Array<String> paths :Function callback &opt :Array<PDFDocument> pdfs]
     (unless pdfs (set pdfs []))
     (deflocal nextPdf (paths.shift))
-    (print nextPdf)
+    (if (nextPdf.endsWith ".pdf")
-    (.then (PDFDocument.load (Fs.readFileSync nextPdf))
+            (awaitLet [pdf (PDFDocument.load (Fs.readFileSync (print nextPdf)))]
-        (lambda [pdf]
                 (pdfs.push pdf)
-            (if paths (loadAll paths callback pdfs)
+                (if paths
+                        (loadAll paths callback pdfs)
                     (callback pdfs)))
-        (lambda [error]
+        (when paths
-            (throw #|'error $error loading $nextPdf'|#))))
+            (loadAll paths callback pdfs))))
 
 (defun main []
     (let [[sourceDir numPages] (Sys.args)]
         (loadAll (for file (Fs.readdirSync sourceDir) (+ sourceDir "/" file))
             (lambda [:Array<PDFDocument> inputPdfs]
-                // TODO make an awaitLet macro that .thens a promise or chain of promises (so the bindings are sequential) into a binding
+                (awaitLet [saladPdf (PDFDocument.create)
-                (.then (PDFDocument.create) (lambda [saladPdf]
+                            pages (Promise.all
-                    (.then 
+                                (for _ (range 0 (Std.parseInt numPages))
-                        (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]))))
+                                        (saladPdf.copyPages pdf [page]))))]
-                        (lambda [pages]
                     (doFor page pages (saladPdf.addPage (first page)))
-                            (.then (saladPdf.save) (lambda [bytesOut]
+                    (awaitLet [bytesOut (saladPdf.save)]
-                                (Fs.writeFileSync "out.pdf" bytesOut)))))))))))
+                        (Fs.writeFileSync "out.pdf" bytesOut)))))))