DRY bindingList() extractor

src/kiss/Helpers.hx

@@ -347,4 +347,13 @@ class Helpers {
             begin: (exps:Array<ReaderExp>) -> CallExp(Symbol("begin").withPosOf(posRef), exps).withPosOf(posRef)
         };
     }
+
+    public static function bindingList(exp:ReaderExp, forThis:String):Array<ReaderExp> {
+        return switch (exp.def) {
+            case ListExp(bindingExps) if (bindingExps.length > 0 && bindingExps.length % 2 == 0):
+                bindingExps;
+            default:
+                throw CompileError.fromExp(exp, '$forThis bindings should be a list expression with an even number of sub expressions (at least 2)');
+        };
+    }
 }

src/kiss/Macros.hx

@@ -424,13 +424,7 @@ class Macros {
         // TODO use expBuilder()
         function awaitLet(wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) {
             wholeExp.checkNumArgs(2, null, "(awaitLet [[promise bindings...]] [body...])");
-            // TODO make a dry bindingList extractor function
-            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 bindingList = exps[0].bindingList("awaitLet");
             var firstName = bindingList.shift();
             var firstValue = bindingList.shift();
             return CallExp(FieldExp("then", firstValue).withPosOf(wholeExp), [

src/kiss/SpecialForms.hx

@@ -166,12 +166,7 @@ class SpecialForms {
 
         map["let"] = (wholeExp:ReaderExp, args:Array<ReaderExp>, k:KissState) -> {
             wholeExp.checkNumArgs(2, null, "(let [[bindings...]] [body...])");
-            var bindingList = switch (args[0].def) {
-                case ListExp(bindingExps) if (bindingExps.length > 0 && bindingExps.length % 2 == 0):
-                    bindingExps;
-                default:
-                    throw CompileError.fromExp(args[0], 'let bindings should be a list expression with an even number of sub expressions');
-            };
+            var bindingList = args[0].bindingList("let");
             var bindingPairs = bindingList.groups(2);
             var varDefs = [];
             for (bindingPair in bindingPairs) {