Parse multi-clause match expressions

src/ludus/parser.clj

@@ -448,24 +448,48 @@
 
 (defn- parse-match-clause [parser]
   (let [pattern (parse-pattern parser)
-    rarrow (expect* #{::token/rarrow} "Expected arrow in match clause" pattern)
+        rarrow (expect* #{::token/rarrow} "Expected arrow after pattern" pattern)
         ]
     (if (:success rarrow)
       (let [body (parse-expr (:parser rarrow))]
         (assoc body ::ast {::ast/type ::ast/clause
                            :pattern (::ast pattern) :body (::ast body)})
         )
-      (panic rarrow "Expected -> in match clause. Clauses must be in the form pattern -> expression")
+      (panic pattern "Expected -> in match clause. Clauses must be in the form pattern -> expression" #{::token/newline ::token/rbrace})
+      )
+    ))
+
+(defn- parse-match-clauses [parser]
+  (loop [
+         parser (accept-many #{::token/newline} (advance parser))
+         clauses []]
+    (let [curr (current parser)]
+      (case (::token/type curr)
+        ::token/rbrace
+        (assoc parser ::ast {::ast/type ::ast/clauses :clauses clauses})
+
+        ::token/newline
+        (recur (accept-many #{::token/newline} parser) clauses)
+        
+        (let [clause (parse-match-clause parser)]
+          (recur (accept-many #{::token/newline} clause) (conj clauses (::ast clause)))
+          )
+        )
       )
     ))
 
 (defn- parse-match [parser]
-  (let [match-expr (parse-expr (advance parser) #{::token/lbrace ::token/lparen})
+  (let [match-expr (parse-expr (advance parser) #{::token/with})
         match-header (expect* #{::token/with} "Expected with" match-expr)]
     (if (:success match-header)
       (let [clauses (:parser match-header)]
         (if (= (token-type clauses) ::token/lbrace)
-          (println "one or many clauses")
+          ;; match expression with one or many clauses in braces
+          (let [clauses (parse-match-clauses clauses)]
+            (assoc clauses ::ast {::ast/type ::ast/match
+                                  :expr (::ast match-expr)
+                                  :clauses (get-in clauses [::ast :clauses])}))
+          ;; match expression with single match clause
           (let [clause (parse-match-clause clauses)]
             (assoc clause ::ast {::ast/type ::ast/match
                                  :expr (::ast match-expr)
@@ -478,19 +502,22 @@
 
 (defn- parse-expr 
   ([parser] (parse-expr parser sync-on))
-  ([parser sync-on] (let [token (current parser)]
+  ([parser sync-on] 
+   (let [token (current parser)]
      (case (::token/type token)
   
        (::token/number ::token/string)
        (parse-atom parser)
   
-                        ::token/keyword (let [next (peek parser)
+       ::token/keyword 
+       (let [next (peek parser)
              type (::token/type next)]
          (if (= type ::token/lparen)
            (parse-synthetic parser)
            (parse-atom parser)))
   
-                        ::token/word (let [next (peek parser)
+       ::token/word 
+       (let [next (peek parser)
              type (::token/type next)]
          (case type
            (::token/lparen ::token/keyword) (parse-synthetic parser)
@@ -538,10 +565,10 @@
 
 (do
   (def pp pp/pprint)
-  (def source "match foo with (foo, bar, 0) -> {
-    let foo = bar
-    if foo then bar else baz
-    :foo
+  (def source "match foo with {
+      _ -> foo
+      foo () -> bar
+      () -> baz
     }")
   (def lexed (scanner/scan source))
   (def tokens (:tokens lexed))