Add splats to list patterns in parser

src/ludus/parser.clj

@@ -484,17 +484,45 @@
 
 (def sync-pattern (s/union sync-on #{::token/equals ::token/rarrow}))
 
+(defn- parse-splat-pattern [origin]
+  (let [splatted (advance origin)]
+    (case (token-type splatted)
+      ::token/word 
+      (assoc (advance splatted) ::ast 
+        {::ast/type ::ast/splat 
+         :token (current origin) 
+         :into (::ast (parse-word splatted))})
+
+      ::token/placeholder
+      (assoc (advance splatted) ::ast
+        {::ast/type ::ast/splat
+         :token (current origin)
+         :into {::ast/type ::ast/placeholder :token (current splatted)}})
+
+      (::token/comma ::token/newline ::token/rbrace ::token/rparen ::token/rbracket)
+      (assoc splatted ::ast
+        {::ast/type ::ast/splat
+         :token (current origin)
+         :into {::ast/type ::ast/placeholder :token (current origin)}})
+
+      (panic origin "Splat patterns may only splat into words or placeholders.")
+      )))
+
 (defn- parse-list-pattern [origin]
   (loop [parser (accept-many #{::token/newline ::token/comma} (advance origin))
          members []
          current_member nil]
     (let [curr (current parser)]
       (case (token-type parser)
-        ::token/rbracket (let [ms (add-member members current_member)]
+        ::token/rbracket
+        (let [ms (add-member members current_member)]
+          (if (not-any? #(= (::ast/type %) ::ast/splat) (drop-last ms))
             (assoc (advance parser) ::ast
-                                  {::ast/type ::ast/list
+              {::ast/type ::ast/tuple
                :token (current origin)
-                                   :members ms}))
+               :length (count ms)
+               :members ms})
+            (panic parser "A splat my only appear once in a pattern, at the end of a pattern.")))
 
         (::token/comma ::token/newline)
         (recur
@@ -507,6 +535,10 @@
         ::token/eof
         (panic (assoc origin ::errors (::errors parser)) "Unterminated list pattern" ::token/eof)
 
+        ::token/splat
+        (let [splatted (parse-splat-pattern parser)]
+          (recur splatted members (::ast splatted)))
+
         (let [parsed (parse-pattern parser)]
           (recur parsed members (::ast parsed)))))))
 
@@ -584,19 +616,22 @@
 
         (panic parser "Struct patterns may only include single words or keyword+pattern pairs." #{::token/rbrace})))))
 
+
 (defn- parse-tuple-pattern [origin]
   (loop [parser (accept-many #{::token/newline ::token/comma} (advance origin))
          members []
          current_member nil]
     (let [curr (current parser)]
       (case (token-type parser)
-        ::token/rparen (let [ms (add-member members current_member)]
+        ::token/rparen 
+        (let [ms (add-member members current_member)]
             (assoc (advance parser) ::ast
               {::ast/type ::ast/tuple
                :token (current origin)
                :length (count ms)
                :members ms}))
           
+
         (::token/comma ::token/newline)
         (recur
           (accept-many #{::token/comma ::token/newline} parser)
@@ -1070,10 +1105,9 @@
     (parser)
     (parse-script)))
 
-(comment
+(do
   (def pp pp/pprint)
-  (def source "if let foo = bar then foo else bar")
+  (def source "let [a, b, (c, d), ...e] = [1, 2, (4, 5), 6]")
-
 
   (println "")
   (println "")