fix: don`t overlap "close"

pkg/tokenizer/tokenizer.go

@@ -2,11 +2,16 @@ package tokenizer
 
 import (
 	"fmt"
+	"strings"
 	"unicode"
 
 	"git.maximhutz.com/max/lambda/pkg/iterator"
 )
 
+func isVariable(r rune) bool {
+	return unicode.IsLetter(r) || unicode.IsNumber(r)
+}
+
 func getToken(i *iterator.Iterator[rune]) (*Token, error) {
 	if i.IsDone() {
 		return nil, nil
@@ -51,29 +56,25 @@ func getToken(i *iterator.Iterator[rune]) (*Token, error) {
 	}
 
 	// Otherwise, it is an atom.
-	atom := string(letter)
+	atom := strings.Builder{}
 	index := i.Index()
-	for {
-		if i.IsDone() {
-			return &Token{
-				Index: index,
-				Type:  TokenVariable,
-				Value: atom,
-			}, nil
-		}
-
+	for !i.IsDone() {
 		pop, err := i.Peek()
-		if err != nil || unicode.IsSpace(pop) || unicode.IsPunct(pop) {
-			return &Token{
-				Index: index,
-				Type:  TokenVariable,
-				Value: atom,
-			}, nil
+		if err != nil || !isVariable(pop) {
+			break
 		}
 
-		i.Next()
-		atom += string(pop)
+		atom.WriteRune(pop)
+		if _, err := i.Next(); err != nil {
+			break
+		}
 	}
+
+	return &Token{
+		Index: index,
+		Type:  TokenVariable,
+		Value: atom.String(),
+	}, nil
 }
 
 func GetTokens(input []rune) ([]Token, []error) {