disable ifLet in defMacro bodies

src/kiss/Kiss.hx

@@ -362,6 +362,19 @@ class Kiss {
     public static function forHScript(k:KissState):KissState {
         var copy = new Cloner().clone(k);
         copy.hscript = true;
+
+        // Also disallow macros that will error when run in hscript:
+        function disableMacro(m:String, reason:String) {
+            copy.macros[m] = (wholeExp:ReaderExp, exps, k) -> {
+                var b = wholeExp.expBuilder();
+                b.callSymbol("throw", [b.str('$m is unavailable in macros because $reason')]);
+            };
+        }
+
+        disableMacro("ifLet", "hscript doesn't support pattern-matching");
+        disableMacro("whenLet", "hscript doesn't support pattern-matching");
+        disableMacro("unlessLet", "hscript doesn't support pattern-matching");
+
         return copy;
     }
 

src/kiss/Macros.hx

@@ -320,6 +320,26 @@ class Macros {
             ]);
         };
 
+        macros["assertThrows"] = (wholeExp:ReaderExp, exps:Array<ReaderExp>, k:KissState) -> {
+            wholeExp.checkNumArgs(1, 2, "(assertThrows [expression] [message])");
+            var b = wholeExp.expBuilder();
+            var expression = exps[0];
+            var basicMessage = '${expression.def.toString()} should have thrown an error';
+            var messageExp = if (exps.length > 1) {
+                b.callSymbol("+", [b.str(basicMessage + ": "), exps[1]]);
+            } else {
+                b.str(basicMessage);
+            };
+
+            b.callSymbol("try", [
+                b.begin([expression, b.callSymbol("throw", [messageExp])]),
+                b.callSymbol("catch", [b.list([b.typed("Dynamic", b.symbol("error"))]),
+                    b.callSymbol("if", [b.callSymbol("=", [b.symbol("error"), messageExp]),
+                            b.callSymbol("throw", [messageExp]),
+                        b.symbol("true")])])
+            ]);
+        };
+
         function stringsThatMatch(exp:ReaderExp, formName:String) {
             return switch (exp.def) {
                 case StrExp(s):

src/test/cases/MacroTestCase.kiss

@@ -80,3 +80,13 @@
 (function _testSetMacroVar []
     (Assert.equals 1 (_testSetMacroVarMacro))
     (Assert.equals 2 (_testSetMacroVarMacro)))
+
+// ifLet and its derivatives should be disabled in defMacro bodies:
+(defMacro _testIfLetDisabledMacro []
+    (assertThrows (ifLet [a "b"] a))
+    (assertThrows (whenLet [a "b"] a))
+    (assertThrows (unlessLet [a "b"] a))
+    `null)
+
+(function _testIfLetDisabled []
+    (_testIfLetDisabledMacro))