optimizations

internal/lexer/lexer.go

@@ -182,9 +182,7 @@ func (l *Lexer) NextToken() token.Token {
 			tok.Type = token.LookupIdent(tok.Literal)
 			return tok
 		} else if isDigit(l.ch) {
-			tok.Type = token.INT
-			tok.Literal = l.readNumber()
-			return tok
+			return l.readNumber()
 		} else {
 			tok = newToken(token.ILLEGAL, l.ch)
 		}
@@ -209,12 +207,22 @@ func (l *Lexer) readIdentifier() string {
 	return l.input[position:l.position]
 }
 
-func (l *Lexer) readNumber() string {
+func (l *Lexer) readNumber() token.Token {
 	position := l.position
 	for isDigit(l.ch) {
 		l.readChar()
 	}
-	return l.input[position:l.position]
+	intPart := l.input[position:l.position]
+	if l.ch == '.' {
+		l.readChar()
+		position := l.position
+		for isDigit(l.ch) {
+			l.readChar()
+		}
+		fracPart := l.input[position:l.position]
+		return token.Token{Type: token.FLOAT, Literal: intPart + "." + fracPart}
+	}
+	return token.Token{Type: token.INT, Literal: intPart}
 }
 
 func isLetter(ch byte) bool {