tightening code around kvrfs, x/for now leverages kvreducibles on inner colls

README.md

@@ -15,7 +15,7 @@ Transducing context: `transjuxt` (for performing several transductions in a sing
 Add this dependency to your project:
 
 ```clj
-[net.cgrand/xforms "0.2.0"]
+[net.cgrand/xforms "0.3.0"]
 ```
 
 ```clj

src/net/cgrand/xforms.clj

@@ -12,38 +12,36 @@
   (let [rf (gensym 'rf)
         acc (gensym 'acc)
         pair? #(and (vector? %) (= 2 (clj/count %)))
+        destructuring-pair? (every-pred pair?
+                              #(not-any? (some-fn keyword? #{'&}) %))
         build (fn [init]
                 (clj/reduce (fn [body [expr binding]]
                       (case binding
                         :let `(let ~expr ~body)
                         :when `(if ~expr ~body ~acc)
                         :while `(if ~expr ~body (reduced ~acc))
-                        `(clj/reduce (fn [~acc ~binding] ~body) ~acc ~expr)))
+                        (if (destructuring-pair? binding)
+                          `(let [expr# ~expr]
+                             (if (and (map? expr#) (satisfies? clojure.core.protocols/IKVReduce expr#))
+                               (clj/reduce-kv (fn [~acc ~@binding] ~body) ~acc expr#)
+                               (clj/reduce (fn [~acc ~binding] ~body) ~acc expr#)))
+                          `(clj/reduce (fn [~acc ~binding] ~body) ~acc ~expr))))
                   init (clj/partition 2 (rseq (vec seq-exprs)))))
-        body (build `(~rf ~acc ~body-expr))
+        body (if (and (pair? body-expr) (nil? (meta body-expr)))
-        kvbody (when (pair? body-expr) (build `(~rf ~acc ~@body-expr)))
+               (build `(~rf ~acc ~@body-expr))
-        fnsym (if (and (pair? binding) (not (some keyword? binding)) (not (some #{'&} (filter symbol? binding)))) `kvrf `fn)]
+               (build `(~rf ~acc ~body-expr)))]
-    (if kvbody
     `(fn [~rf]
-         (if-some [~rf (some-kvrf ~rf)]
+       (let [~rf (ensure-kvrf ~rf)]
-           (~fnsym
+         (kvrf
-             ([] (~rf))
-             ([~acc] (~rf ~acc))
-             ([~acc ~binding] ~kvbody)
-             ~@(when (= fnsym `kvrf) [`([~acc ~@binding] ~kvbody)]))
-           (~fnsym
            ([] (~rf))
            ([~acc] (~rf ~acc))
            ([~acc ~binding] ~body)
-             ~@(when (= fnsym `kvrf) [`([~acc ~@binding] ~body)]))))
+           ~(if (destructuring-pair? binding)
-      `(fn [~rf]
+              `([~acc ~@binding] ~body)
-         (~fnsym
+              `([~acc k# v#]
-           ([] (~rf))
+                 (let [~binding (clojure.lang.MapEntry. k# v#)] ~body))))))))
-           ([~acc] (~rf ~acc))
-           ([~acc ~binding] ~body)
-           ~@(when (= fnsym `kvrf) [`([~acc ~@binding] ~body)]))))))
 
-(defprotocol KvRfable "Protocol for reducing fns that takes key and val as separate arguments."
+(defprotocol KvRfable "Protocol for reducing fns that accept key and val as separate arguments."
   (some-kvrf [f] "Returns a kvrf or nil"))
 
 (extend-protocol KvRfable
@@ -76,7 +74,7 @@
   ([f]
     (fn [rf]
       (let [vacc (volatile! (f))]
-        (if-some [f (some-kvrf f)]
+        (let [f (ensure-kvrf f)]
           (kvrf
             ([] (rf))
             ([acc] (rf (unreduced (rf acc (f (unreduced @vacc))))))
@@ -86,13 +84,6 @@
                 acc))
             ([acc k v]
               (if (reduced? (vswap! vacc f k v))
-                (reduced acc)
-                acc)))
-          (fn
-            ([] (rf))
-            ([acc] (rf (unreduced (rf acc (f (unreduced @vacc))))))
-            ([acc x]
-              (if (reduced? (vswap! vacc f x))
                 (reduced acc)
                 acc)))))))
   ([f init]
@@ -159,9 +150,8 @@
 (defn- multiplexable
   "Creates a multiplexable reducing function (doesn't init or complete the uderlying rf)."
   [rf]
-  (if-some [rf (some-kvrf rf)]
+  (let [rf (ensure-kvrf rf)]
-    (kvrf ([]) ([acc] acc) ([acc x] (rf acc x)) ([acc k v] (rf acc k v)))
+    (kvrf ([]) ([acc] acc) ([acc x] (rf acc x)) ([acc k v] (rf acc k v))))) ; no init no complete rf
-    (fn ([]) ([acc] acc) ([acc x] (rf acc x))))) ; no init no complete rf
 
 (defn by-key
   "Returns a transducer which partitions items according to kfn.
@@ -376,7 +366,6 @@
   "Returns a reducing fn which compute all rfns at once and whose final return
    value is a vector of the final return values of each rfns."
   [& rfns]
-  (if (some some-kvrf rfns)
   (let [rfns (mapv ensure-kvrf rfns)]
     (kvrf
       ([] (mapv #(vector % (volatile! (%))) rfns))
@@ -390,16 +379,7 @@
         (let [some-unreduced (clj/reduce (fn [some-unreduced [rf vacc]] 
                                            (when-not (reduced? @vacc) (vswap! vacc rf k v) true))
                                false acc)]
-            (if some-unreduced acc (reduced acc))))))
+          (if some-unreduced acc (reduced acc)))))))
-    (let [rfns (vec rfns)]
-      (fn
-        ([] (mapv #(vector % (volatile! (%))) rfns))
-        ([acc] (mapv (fn [[rf vacc]] (rf (unreduced @vacc))) acc))
-        ([acc x]
-          (let [some-unreduced (clj/reduce (fn [some-unreduced [rf vacc]] 
-                                             (when-not (reduced? @vacc) (vswap! vacc rf x) true))
-                                 false acc)]
-            (if some-unreduced acc (reduced acc))))))))
 
 (defn multiplex
   [xforms-map]
@@ -439,16 +419,12 @@
   [& key-rfns]
   (let [f (apply juxt (take-nth 2 (next key-rfns)))
         keys (vec (take-nth 2 key-rfns))]
-    (if-some [f (some-kvrf f)]
+    (let [f (ensure-kvrf f)]
       (kvrf
         ([] (f))
         ([acc] (zipmap keys (f acc)))
         ([acc x] (f acc x))
-        ([acc k v] (f acc k v)))
+        ([acc k v] (f acc k v))))))
-      (fn
-        ([] (f))
-        ([acc] (zipmap keys (f acc)))
-        ([acc x] (f acc x))))))
 
 (defn first
   "Reducing function that returns the first value or nil if none."

test/net/cgrand/xforms_test.clj

@@ -102,3 +102,7 @@
   [{:ts 3.5} {:ts 3.75} {:ts 4.0} {:ts 4.25}] ; t =  4.25
   [{:ts 3.75} {:ts 4.0} {:ts 4.25} {:ts 4.5}] ; t =  4.5
   [{:ts 4.0} {:ts 4.25} {:ts 4.5} {:ts 4.75}]]))) ; t =  4.75
+
+(deftest do-not-kvreduce-vectors
+  (is (= {0 nil 1 nil} (x/into {} (x/for [[k v] %] [k v]) [[0] [1]])))
+  (is (= {0 nil 1 nil} (x/into {} (x/for [_ % [k v] [[0] [1]]] [k v]) ["a"]))))