allow := (hi walrus) as alias for = / assign (#54)

lexer/lexer.go

@@ -21,7 +21,7 @@ func NewLineMode(input string) *Lexer {
 	return &Lexer{input: input, lineMode: true}
 }
 
-func (l *Lexer) NextToken() token.Token { //nolint:funlen // many cases to lex.
+func (l *Lexer) NextToken() token.Token { //nolint:funlen,gocyclo // many cases to lex.
 	l.skipWhitespace()
 
 	ch := l.readChar()
@@ -87,6 +87,10 @@ func (l *Lexer) NextToken() token.Token { //nolint:funlen // many cases to lex.
 	case ']':
 		return newToken(token.RBRACKET, ch)
 	case ':':
+		if l.peekChar() == '=' { // semi hacky treat := as = (without changing literal etc so tests work with either)
+			nextChar := l.readChar()
+			return newToken(token.ASSIGN, nextChar)
+		}
 		return newToken(token.COLON, ch)
 	case '"':
 		return token.Token{Type: token.STRING, Literal: l.readString()}

lexer/lexer_test.go

@@ -35,6 +35,7 @@ a2=3
 {"foo": "bar"}
 return // nil return
 macro(x, y) { x + y }
+a3:=5
 `
 
 	tests := []struct {
@@ -142,6 +143,9 @@ macro(x, y) { x + y }
 		{token.PLUS, "+"},
 		{token.IDENT, "y"},
 		{token.RBRACE, "}"},
+		{token.IDENT, "a3"},
+		{token.ASSIGN, "="}, // `:=` changed to `=`.
+		{token.INT, "5"},
 		{token.EOF, ""},
 	}
 

repl/repl_test.go

@@ -30,7 +30,7 @@ Factorial of 5 is 120` + " \n120\n" // there is an extra space before \n that vs
 }
 
 func TestEvalStringParsingError(t *testing.T) {
-	s := `x:=3`
+	s := `.`
 	expected := ""
 	res, errs := repl.EvalString(s)
 	if len(errs) == 0 {