Added equals assignment operator

The set phrase will be removed and just replaced with a single
equals sign. Double equals will be used for comparison. This will
be much easier to understand.

lexer/lexer.go

@@ -275,9 +275,15 @@ func (lexer *LexingOperation) tokenizeSymbolBeginning () (err error) {
 		lexer.addToken(token)
 	case '=':
 		token := lexer.newToken()
-		token.kind = TokenKindEqualTo
-		lexer.addToken(token)
 		err = lexer.nextRune()
+		if err != nil { return }
+		token.kind = TokenKindAssignment
+		if lexer.char == '=' {
+			token.kind = TokenKindEqualTo
+			err = lexer.nextRune()
+			token.location.SetWidth(2)
+		}
+		lexer.addToken(token)
 	case '<':
 		token := lexer.newToken()
 		err = lexer.nextRune()

lexer/lexer_test.go

@@ -155,7 +155,8 @@ func TestTokenizeAll (test *testing.T) {
 		quickToken(2, TokenKindPercentAssignment, nil),
 		quickToken(1, TokenKindTilde, nil),
 		quickToken(2, TokenKindTildeAssignment, nil),
-		quickToken(1, TokenKindEqualTo, nil),
+		quickToken(1, TokenKindAssignment, nil),
+		quickToken(2, TokenKindEqualTo, nil),
 		quickToken(2, TokenKindNotEqualTo, nil),
 		quickToken(1, TokenKindLessThan, nil),
 		quickToken(2, TokenKindLessThanEqualTo, nil),

lexer/token.go

@@ -47,6 +47,7 @@ const (
         TokenKindTilde
         TokenKindTildeAssignment
 
+        TokenKindAssignment
         TokenKindEqualTo
         TokenKindNotEqualTo
         TokenKindLessThanEqualTo
@@ -197,6 +198,8 @@ func (tokenKind TokenKind) Describe () (description string) {
 		description = "Tilde"
 	case TokenKindTildeAssignment:
 		description = "TildeAssignment"
+	case TokenKindAssignment:
+		description = "Assignment"
 	case TokenKindEqualTo:
 		description = "EqualTo"
 	case TokenKindNotEqualTo:

tests/lexer/all.arf

@@ -1,3 +1,3 @@
 :arf
 --- rw -> -349820394 932748397 239485.37520 "hello world!\n" 'E' helloWorld:.,..[]{}
-+ - ++ -- * / @ ! % %= ~ ~= = != < <= << <<= > >= >> >>= | |= || & &= && ^ ^=
++ - ++ -- * / @ ! % %= ~ ~= = == != < <= << <<= > >= >> >>= | |= || & &= && ^ ^=