[Bootstrap] Add a basic PrintError function to print error messages with the traceback

bootstrap/examples/hello-world.srn

@@ -5,14 +5,24 @@
      (fn (name)
          (println "hello" name)))
 
+(def a1
+     (fn (x y)
+         x))
+
 (defmacro defn
   (name args &body)
-  (list 'def name (cons 'fn (cons args body))))
+  (list 'do
+        (list 'def name (cons 'fn (cons args body)))
+        (list 'a1 ~args)))
+
+
+
+
 
 (defn pp (x y)
   (println x))
 
 (def main
      (fn (&args)
-         (pp "sam")
+         (pp "sam" 2)
          (hello-world "world")))

bootstrap/pkg/ast/ast.go

@@ -66,7 +66,7 @@ func (s *Source) GetLine(linenum int) string {
 	if linenum > 0 && linenum < len(lines) {
 		return lines[linenum-1]
 	}
-	return "!!!"
+	return "----"
 }
 
 func (s *Source) LineNumberFor(pos int) int {
@@ -96,13 +96,7 @@ func (s *Source) LineNumberFor(pos int) int {
 		return -1
 	}
 
-	result := sort.Search(len(*s.LineIndex), func(i int) bool {
-		if i == 0 {
-			return pos < (*s.LineIndex)[i]
-		} else {
-			return (*s.LineIndex)[i-1] < pos && pos < (*s.LineIndex)[i]
-		}
-	})
+	result := sort.SearchInts(*s.LineIndex, pos)
 
 	// We've found something
 	if result > -1 {
@@ -111,7 +105,6 @@ func (s *Source) LineNumberFor(pos int) int {
 	}
 
 	return result
-
 }
 
 type Location struct {

bootstrap/pkg/core/core.go

@@ -118,7 +118,7 @@ func Run(flags map[string]bool, args []string) {
 	}
 
 	rt := MakeRuntime([]string{cwd}, flags)
-	rt.CreateNS("user", "REPL", true)
+	rt.CreateNS("user", "RUN", true)
 
 	if len(args) == 0 {
 
@@ -137,12 +137,8 @@ func Run(flags map[string]bool, args []string) {
 	}
 
 	tmpl, e := template.New("run").Parse(
-		`(def run-main
-     (fn ()
-       (require '({{.NS}} n))
-       (n/main {{.Args}})))
-
-(run-main)`,
+		`(require '({{.NS}} n))
+(n/main {{.Args}})`,
 	)
 
 	if e != nil {
@@ -160,7 +156,7 @@ func Run(flags map[string]bool, args []string) {
 		fmt.Println(buf.String())
 	}
 
-	ast, err := ReadString("*RUN*", buf.String())
+	ast, err := ReadString("*INTERNAL*", buf.String())
 
 	if err != nil {
 		PrintError(rt, err)

bootstrap/pkg/core/errors.go

@@ -49,6 +49,10 @@ const (
 	RuntimeError
 )
 
+func (e ErrType) String() string {
+	return [...]string{"Syntax Error", "Semantic Error", "Runtime Error"}[e]
+}
+
 // IError defines the necessary functionality of the internal errors.
 type IError interface {
 	// In order to point to a specific point in the input

bootstrap/pkg/core/parser.go

@@ -29,6 +29,15 @@ package core
 // * Add the support for strings
 // * Add the support for kewords
 // * Add a shortcut for the `deref` function like `@x` => `(deref x)`
+// * A line of comment at the end of a list definition causes a synxtax error.
+//   We need to fix it. For example:
+//   (asdb xyz
+//   ;; problematic comment line
+//   )
+// Will fails. The reason being we call `readExpr` in `readList` and in the
+// `readExpr` when we read a line of comment we jump to a label and try to
+// read another expr which in our case it would read the end of list and throw
+// and error
 
 import (
 	"strings"
@@ -325,6 +334,8 @@ func readNumber(parser IParsable, neg bool) (IExpr, IError) {
 		r := rune(char[0])
 		if unicode.IsDigit(r) {
 			result = result + *c
+		} else if isValidForSymbol(char) {
+			return nil, makeErrorAtPoint(parser, "Illegal token while scanning for a number.")
 		} else {
 			parser.back()
 			break

bootstrap/pkg/core/printer.go

@@ -64,12 +64,43 @@ func Println(rt *Runtime, ast ...IRepresentable) {
 	fmt.Println(toPrintableString(ast...))
 }
 
-func PrintError(rt *Runtime, err IError) {
+func printError(rt *Runtime, err IError, stage int) {
+	loc := err.GetLocation()
+	source := loc.GetSource()
 
+	startline := source.LineNumberFor(loc.GetStart())
+
+	if startline > 0 {
+		startline -= 1
+	}
+
+	endline := source.LineNumberFor(loc.GetEnd()) + 1
+
+	var lines string
+	for i := startline; i <= endline; i++ {
+		line := source.GetLine(i)
+		if line != "----" {
+			lines += fmt.Sprintf("%d:\t%s\n", i, line)
+		}
+	}
+
+	color.Yellow.Printf(
+		"%d: At '%s'\n",
+		stage,
+		source.Path,
+	)
+
+	color.White.Printf("%s\n", lines)
+
+	errTag := color.Red.Sprint(err.GetErrType().String())
+	fmt.Printf("%s: %s\nAt: %d to %d\n", errTag, err.String(), loc.GetStart(), loc.GetEnd())
+
+}
+
+func printErrorWithTraceBack(rt *Runtime, err IError) {
 	trace := err.GetStackTrace()
-	fmt.Println(err)
+
 	for i, t := range *trace {
-		fmt.Println(*t)
 		caller := t.Caller
 		callerLoc := caller.GetLocation()
 		callerSource := callerLoc.GetSource()
@@ -84,23 +115,36 @@ func PrintError(rt *Runtime, err IError) {
 
 		var lines string
 		for i := startline; i <= endline; i++ {
-			fmt.Println(">>>>>>>>>> ", err)
 			fLoc := t.Fn.GetLocation()
-			fmt.Println(">>>>>>>>>> ", fLoc, fLoc.GetSource())
-
-			lines += fmt.Sprintf("%d:\t%s\n", i, fLoc.GetSource().GetLine(i))
+			line := fLoc.GetSource().GetLine(i)
+			if line != "----" {
+				lines += fmt.Sprintf("%d:\t%s\n", i, line)
+			}
 		}
 
 		color.Yellow.Printf(
-			"%d: In function '%s' at '%s'\n",
+			"%d: In function '%s' at '%s':%d\n",
 			i,
 			t.Fn.GetName(),
 			callerLoc.GetSource().Path,
+			callerSource.LineNumberFor(callerLoc.GetStart()),
 		)
 		color.White.Printf("%s\n", lines)
 	}
 	loc := err.GetLocation()
-
-	errTag := color.Red.Sprint("ERROR")
+	errTag := color.Red.Sprint(err.GetErrType().String())
 	fmt.Printf("%s: %s\nAt: %d to %d\n", errTag, err.String(), loc.GetStart(), loc.GetEnd())
 }
+
+func PrintError(rt *Runtime, err IError) {
+	switch err.GetErrType() {
+	case SyntaxError, SemanticError:
+		printError(rt, err, 0)
+		return
+	case RuntimeError:
+		printErrorWithTraceBack(rt, err)
+		return
+	default:
+		panic(fmt.Sprintf("Don't know about error type '%d'", err.GetErrType()))
+	}
+}