added missing keyword and type definition

according to my experiments with the current playground, the keyword infer is missing and Expression must be explicitly introduced, see: https://langium.org/playground?grammar=OYJwhgthYgBAcgVwgUxASwMYFEAeAHEFAZ2PQHsA7YgKBpUoBcQBPWAWXIBMUAbALhqxhsYozCMUqJsQDUAXgCCXLukYVKsABQByADQ7R4ydMZylKtRoCUAKgDcdZavVVYRRohDVYeQiTIqQRFYAGV0CHxeFD8iUg1tAG90SgAzNFhnKyoAOmjUxnlMLyImAF9YHVlDDGAAC0LwyOjYgJsHOiaomII4wMpgkR1dTMtXTR1rQwAfWAA3MF5EFHl4AFV2ACFsACVHGhTJEFSwTBRfXra3RLK6I4gUxYQN7Z3%2BWAB6AG0ABgBaACcAF1ZB99nV0CoGLB7o9eLAAOqhd4fAA6cjBNAhUM0sMoT3YABkAPoAYQA8ux2Nh4AAVFGotG2L7o1GhIG2AD8qNsjMx2J4uLQD3x8NCJIpVJp9M%2BjMZXwAeqjKKiQBzMUA&content=IwAg1CBMA0BQAsdLhAZhY2yIAp0XgEokU9Cg
JohannesMeierSE · Mar 24, 2023 · 0115ff8 · 0115ff8
1 parent d8666a1
commit 0115ff8
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/hugo/content/docs/grammar-language.md b/hugo/content/docs/grammar-language.md
@@ -251,8 +251,9 @@ SimpleExpression:
 ```
 Unfortunately, *left-factoring* does not come without consequences and can lead to the generation of unwanted nodes. It is possible to "clean" the tree by using *tree-rewriting actions*.
 ```langium
+interface Expression {}
 Addition returns Expression:
-    SimpleExpression ({Addition.left=current} '+' right=SimpleExpression)*;
+    SimpleExpression ({infer Addition.left=current} '+' right=SimpleExpression)*;
 
 SimpleExpression:
     '(' Addition ')' | value=INT;