Ah, right associative..

README.md

@@ -205,7 +205,7 @@ Mímir now also contains an [experimental parser](https://github.com/hraberg/mim
 See [`mimir.test.parse`](https://github.com/hraberg/mimir/blob/master/test/mimir/test/parse.clj) for examples (but an absolute lack of proper tests). Many things doesn't work properly yet, and the theoretical foundations are shaky to say the least. It doesn't support left-recursion - and a few things are broken. I'm currently backing off to read a few papers, so the references list will hopefully be updated in a few days, once I understand more about what I don't understand.
 
 ```clojure
-(def right-recursive
+(def right-recursive                   ;; Note: right associative.
   (create-parser                       ;; This returns a parser function.
    {:suppress-tags true}               ;; Options, can also be given when invoking, see below.
 

test/mimir/test/parse.clj

@@ -37,19 +37,19 @@
 ;; | Decimal
 ;; Decimal → '0' | ... | '9'
 
-;; Should arguebly use choice instead of #{}
 (def peg-expression (create-parser
                      {:suppress-tags true}
 
-                     :additive  #{[:multitive #"[+-]" :additive]
-                                  :multitive} op
-                     :multitive #{[:primary #"[*/]" :multitive]
-                                  :primary} op
-                     :primary   #{["(" :additive ")"]
-                                  :decimal}
+                     :additive  (choice [:multitive #"[+-]" :additive]
+                                        :multitive) op
+                     :multitive (choice [:primary #"[*/]" :multitive]
+                                        :primary) op
+                     :primary   (choice ["(" :additive ")"]
+                                        :decimal)
                      :decimal   #"[0-9]+" read-string))
 
 ;; This gets wrong precedence, regardless of using choice / OrderedSet or not. So something else.
+;; This also seems right associtive?
 ;; Should return 33.
 (peg-expression "1-2/(3-4)+5*6")
 
@@ -111,6 +111,11 @@
 (right-recursive "1-2/(3-4)+5*6")
 ;; Gives -27, should be 33.
 
+;; Here's a simpler tree that fails:
+;; Gives -4, should be 2.
+(right-recursive "1-2+3")
+;; Actually, the slides says: "Note: This grammar is right-associative." !
+
 ;; But the tree is much nicer, and could hint to the answer:
 (right-recursive "1-2/(3-4)+5*6" :grammar-actions false :suppress-tags false)