more keywords

lexer/lexer.go

@@ -37,6 +37,18 @@ func (l *Lexer) NextToken() token.Token {
 		tok = newToken(token.ASSIGN, l.ch)
 	case '+':
 		tok = newToken(token.PLUS, l.ch)
+	case '-':
+		tok = newToken(token.MINUS, l.ch)
+	case '!':
+		tok = newToken(token.BANG, l.ch)
+	case '/':
+		tok = newToken(token.SLASH, l.ch)
+	case '*':
+		tok = newToken(token.ASTERISK, l.ch)
+	case '<':
+		tok = newToken(token.LT, l.ch)
+	case '>':
+		tok = newToken(token.GT, l.ch)
 	case '(':
 		tok = newToken(token.LPAREN, l.ch)
 	case ')':

lexer/lexer_test.go

@@ -14,6 +14,15 @@ let add = fn(x,y) {
 	x + y;
 };
 let result = add(five, ten);
+!-/*5;
+5 < 10 > 5;
+
+if (5 < 10) {
+    return true;
+} else {
+    return false;
+}
+// [...]
 `
 
 	tests := []struct {
@@ -56,6 +65,18 @@ let result = add(five, ten);
 		{token.IDENT, "ten"},
 		{token.RPAREN, ")"},
 		{token.SEMICOLON, ";"},
+		{token.BANG, "!"},
+		{token.MINUS, "-"},
+		{token.SLASH, "/"},
+		{token.ASTERISK, "*"},
+		{token.INT, "5"},
+		{token.SEMICOLON, ";"},
+		{token.INT, "5"},
+		{token.LT, "<"},
+		{token.INT, "10"},
+		{token.GT, ">"},
+		{token.INT, "5"},
+		{token.SEMICOLON, ";"},
 		{token.EOF, ""},
 	}
 

token/token.go

@@ -18,6 +18,13 @@ const (
 	//OPERATORS
 	ASSIGN   = "="
 	PLUS     = "+"
+	MINUS    = "-"
+	BANG     = "!"
+	ASTERISK = "*"
+	SLASH    = "/"
+
+	LT = "<"
+	GT = ">"
 
 	//DELIM
 	COMMA     = ""
@@ -31,11 +38,21 @@ const (
 	// KEYWORDS
 	FUNCTION = "FUNCTION"
 	LET      = "LET"
+	TRUE     = "TRUE"
+	FALSE    = "FALSE"
+	IF       = "IF"
+	ELSE     = "ELSE"
+	RETURN   = "RETURN"
 )
 
 var keywords = map[string]TokenType{
 	"fn":     FUNCTION,
 	"let":    LET,
+	"true":   TRUE,
+	"false":  FALSE,
+	"if":     IF,
+	"else":   ELSE,
+	"return": RETURN,
 }
 
 func LookupIdent(ident string) TokenType {