Standardized CompileError

README.md

@@ -22,6 +22,7 @@ Kiss is a work in progress. (See: [Who should use Kiss?](#who-should-use-kiss))
 - [ ] [Reader macros](https://gist.github.com/chaitanyagupta/9324402)
 - [ ] Plug-and-play with every pure-Haxe library on Haxelib
 - [ ] Smooth FFI with any non-Haxe library you can find or write Haxe bindings for
+- [ ] helpful compiler errors
 
 **Extra goodies:**
 

src/kiss/CompileError.hx

@@ -0,0 +1,41 @@
+package kiss;
+
+import kiss.Reader;
+import kiss.List;
+
+using kiss.Reader;
+
+class CompileError {
+    var exps:List<ReaderExp>;
+    var message:String;
+
+    function new(exps:Array<ReaderExp>, message:String) {
+        this.exps = exps;
+        this.message = message;
+    }
+
+    public static function fromExp(exp:ReaderExp, message:String) {
+        return new CompileError([exp], message);
+    }
+
+    public static function fromArgs(exps:Array<ReaderExp>, message:String) {
+        return new CompileError(exps, message);
+    }
+
+    public function toString() {
+        var posPrefix = switch (exps.length) {
+            case 1:
+                exps[0].pos;
+            default:
+                var justLineAndColumnIdx = exps[-1].pos.indexOf(":") + 1;
+                exps[0].pos + '-' + exps[-1].pos.substr(justLineAndColumnIdx);
+        }
+
+        return '\nKiss compilation failed!\n'
+            + posPrefix
+            + ": "
+            + message
+            + "\nFrom:"
+            + [for (exp in exps) exp.def.toString()].toString();
+    }
+}

src/kiss/FieldForms.hx

@@ -6,6 +6,7 @@ import kiss.Reader;
 import kiss.Types;
 import kiss.Helpers;
 import kiss.Stream;
+import kiss.CompileError;
 
 using kiss.Reader;
 using StringTools;
@@ -40,13 +41,13 @@ class FieldForms {
             case Symbol(name) | TypedExp(_, {pos: _, def: Symbol(name)}):
                 name;
             default:
-                throw 'The first argument to $formName at ${nameExp.pos} should be a variable name or typed variable name';
+                throw CompileError.fromExp(nameExp, 'The first argument to $formName should be a variable name or typed variable name.');
         };
     }
 
     static function varOrProperty(formName:String, position:Position, args:Array<ReaderExp>, convert:ExprConversion):Field {
         if (args.length < 2 || args.length > 3) {
-            throw '$formName with $args at $position has wrong number of arguments';
+            throw CompileError.fromArgs(args, '$formName has wrong number of arguments');
         }
 
         var name = fieldName(formName, args[0]);

src/kiss/Kiss.hx

@@ -9,6 +9,7 @@ import kiss.FieldForms;
 import kiss.SpecialForms;
 import kiss.Macros;
 import kiss.Types;
+import kiss.CompileError;
 
 typedef KissState = {
     className:String,
@@ -24,42 +25,48 @@ class Kiss {
         Build a Haxe class from a corresponding .kiss file
     **/
     macro static public function build(kissFile:String):Array<Field> {
-        var classFields = Context.getBuildFields();
-        var className = Context.getLocalClass().get().name;
+        try {
+            var classFields = Context.getBuildFields();
+            var className = Context.getLocalClass().get().name;
 
-        var stream = new Stream(kissFile);
+            var stream = new Stream(kissFile);
 
-        var k = {
-            className: className,
-            readTable: Reader.builtins(),
-            fieldForms: FieldForms.builtins(),
-            specialForms: SpecialForms.builtins(),
-            macros: Macros.builtins(),
-            convert: null
-        }
-        k.convert = readerExpToHaxeExpr.bind(_, k);
-
-        while (true) {
-            stream.dropWhitespace();
-            if (stream.isEmpty())
-                break;
-            var position = stream.position();
-            var nextExp = Reader.read(stream, k.readTable);
-            #if test
-            trace(nextExp);
-            #end
-            // The last expression might be a comment, in which case None will be returned
-            switch (nextExp) {
-                case Some(nextExp):
-                    var field = readerExpToField(nextExp, position, k);
-                    if (field != null)
-                        classFields.push(field);
-                case None:
-                    stream.dropWhitespace(); // If there was a comment, drop whitespace that comes after
+            var k = {
+                className: className,
+                readTable: Reader.builtins(),
+                fieldForms: FieldForms.builtins(),
+                specialForms: SpecialForms.builtins(),
+                macros: Macros.builtins(),
+                convert: null
             }
-        }
+            k.convert = readerExpToHaxeExpr.bind(_, k);
 
-        return classFields;
+            while (true) {
+                stream.dropWhitespace();
+                if (stream.isEmpty())
+                    break;
+                var position = stream.position();
+                var nextExp = Reader.read(stream, k.readTable);
+                #if test
+                trace(nextExp);
+                #end
+                // The last expression might be a comment, in which case None will be returned
+                switch (nextExp) {
+                    case Some(nextExp):
+                        var field = readerExpToField(nextExp, position, k);
+                        if (field != null)
+                            classFields.push(field);
+                    case None:
+                        stream.dropWhitespace(); // If there was a comment, drop whitespace that comes after
+                }
+            }
+
+            return classFields;
+        } catch (err:CompileError) {
+            Sys.println(err);
+            Sys.exit(1);
+            return null; // Necessary for build() to compile
+        }
     }
 
     static function readerExpToField(exp:ReaderExp, position:Position, k:KissState):Null<Field> {