new: left-inserting pipeline operators.

* stdlib/op.tl (opip-expand): Take arguments which specify
the op and do operators to be inserted. Pass these
through the recursive calls.
(opip, oand): Pass op and do for the new arguments.
(lopip, loand): New macros like opip and oand, but
passing lop and ldo to the expander.
(lflow): New macro.

* autoload.c (op_set_entries): Add autoload entries
for lopip, loand and lflow.

* tests/012/op.tl: A few new tests.

* txr.1: Documented.

* stdlib/doc-syms.tl: Regenerated.

5 files changed, 83 insertions, 20 deletions

diff --git a/autoload.c b/autoload.c
index b87d560a..417f6fb0 100644
--- a/autoload.c
+++ b/autoload.c
@@ -711,7 +711,8 @@ static val op_set_entries(val fun)
   val name[] = {
     lit("op"), lit("do"), lit("lop"), lit("ldo"), lit("ap"), lit("ip"),
     lit("ado"), lit("ido"), lit("ret"), lit("aret"),
-    lit("opip"), lit("oand"), lit("flow"),
+    lit("opip"), lit("oand"), lit("lopip"), lit("loand"),
+    lit("flow"), lit("lflow"),
     nil
   };
   autoload_set(al_fun, name, fun);
diff --git a/stdlib/doc-syms.tl b/stdlib/doc-syms.tl
index 79a52f39..be86e9d7 100644
--- a/stdlib/doc-syms.tl
+++ b/stdlib/doc-syms.tl
@@ -806,7 +806,7 @@
       ("floor" "D-0082")
       ("floor-rem" "N-02DE978F")
       ("floor1" "N-01ED20D1")
-      ("flow" "N-02B2153E")
+      ("flow" "N-0178C76B")
       ("flush" "N-02390935")
       ("flush-stream" "N-03999913")
       ("flusho" "N-0072FF5E")
@@ -1157,6 +1157,7 @@
       ("lexical-macro-p" "N-021EC6D2")
       ("lexical-symacro-p" "N-021EC6D2")
       ("lexical-var-p" "N-021EC6D2")
+      ("lflow" "N-0178C76B")
       ("lgamma" "D-0086")
       ("lib-version" "N-032F57D4")
       ("line" "N-02D5D09D")
@@ -1176,6 +1177,7 @@
       ("load-args-recurse" "N-03067356")
       ("load-for" "N-0020A085")
       ("load-time" "D-0089")
+      ("loand" "N-02C35B52")
       ("loff-t" "N-01153D9E")
       ("log" "D-005A")
       ("log-alert" "N-035D75EC")
@@ -1212,6 +1214,7 @@
       ("long-suffix" "N-00A3183A")
       ("longlong" "N-02299408")
       ("lop" "N-017F3A22")
+      ("lopip" "N-02C35B52")
       ("lset" "N-008216EC")
       ("lstat" "N-006DE1CC")
       ("lutimes" "N-00E96FCF")
@@ -1410,7 +1413,7 @@
       ("o-sync" "N-034BF6C9")
       ("o-trunc" "N-034BF6C9")
       ("o-wronly" "N-034BF6C9")
-      ("oand" "N-01937C5A")
+      ("oand" "N-02C35B52")
       ("obtain" "N-01556613")
       ("obtain*" "N-0102F0EB")
       ("obtain*-block" "N-0102F0EB")
@@ -1440,7 +1443,7 @@
       ("open-tail" "N-0348F89A")
       ("opendir" "N-024AA6F4")
       ("openlog" "N-037AA654")
-      ("opip" "N-01937C5A")
+      ("opip" "N-02C35B52")
       ("opost" "N-03BD477F")
       ("opt" "N-0047F5AB")
       ("opt-desc" "N-03FC5092")
diff --git a/stdlib/op.tl b/stdlib/op.tl
index 2a41fc5a..4b5b0311 100644
--- a/stdlib/op.tl
+++ b/stdlib/op.tl
@@ -231,32 +231,42 @@
           (listp rest)))
     (t nil)))
 
-(defun sys:opip-expand (e clauses)
+(defun sys:opip-expand (e opsym dosym clauses)
   (tree-case clauses
     (nil nil)
     ((c . rest)
      (if (atom c)
-       (cons c (sys:opip-expand e rest))
+       (cons c (sys:opip-expand e opsym dosym rest))
        (let ((sym (car c)))
          (cond
            ((memq sym '(dwim uref qref op do lop ldo ap ip ado ido ret aret))
-            (cons c (sys:opip-expand e rest)))
+            (cons c (sys:opip-expand e opsym dosym rest)))
            ((sys:opip-single-let-p c)
             (tree-bind (t sym) c
-              (sys:opip-expand e ^((let (,sym @1)) ,*rest))))
+              (sys:opip-expand e opsym dosym ^((let (,sym @1)) ,*rest))))
            ((sys:opip-let-p c)
             (tree-bind (t . vars) c
               ^((do let* ,vars
-                  [(opip ,*(sys:opip-expand e rest)) @1]))))
+                  [(opip ,*(sys:opip-expand e opsym dosym rest)) @1]))))
            (t (let ((opdo (if (or (special-operator-p (car c))
-                                  (macro-form-p c e)) 'do 'op)))
-                (cons ^(,opdo ,*c) (sys:opip-expand e rest))))))))))
+                                  (macro-form-p c e)) dosym opsym)))
+                (cons ^(,opdo ,*c) (sys:opip-expand e opsym dosym
+                                                    rest))))))))))
 
 (defmacro opip (:env e . clauses)
-  ^[chain ,*(sys:opip-expand e clauses)])
+  ^[chain ,*(sys:opip-expand e 'op 'do clauses)])
 
 (defmacro oand (:env e . clauses)
-  ^[chand ,*(sys:opip-expand e clauses)])
+  ^[chand ,*(sys:opip-expand e 'op 'do clauses)])
+
+(defmacro lopip (:env e . clauses)
+  ^[chain ,*(sys:opip-expand e 'lop 'ldo clauses)])
+
+(defmacro loand (:env e . clauses)
+  ^[chand ,*(sys:opip-expand e 'lop 'ldo clauses)])
 
 (defmacro flow (val . opip-args)
   ^(call (opip ,*opip-args) ,val))
+
+(defmacro lflow (val . opip-args)
+  ^(call (lopip ,*opip-args) ,val))
diff --git a/tests/012/op.tl b/tests/012/op.tl
index 5501cec4..4e0a8d46 100644
--- a/tests/012/op.tl
+++ b/tests/012/op.tl
@@ -105,3 +105,7 @@
   (flow 10 (+ 1) (let (x @1) (y (* x 2))) (+ x y)) 44
   (flow 10 (+ 1) (let ((x @1) (y (* @1 2))) (+ x y))) 33
   (flow 10 (+ 1) (let ((x @1) (y (* @1 2))))) nil)
+
+(mtest
+  (lflow 10 (- 1) (- 1)) 8
+  (lflow 10 (op - 100) (+ 1)) 91)
diff --git a/txr.1 b/txr.1
index 70a115a2..5a14573f 100644
--- a/txr.1
+++ b/txr.1
@@ -59006,10 +59006,12 @@ functions.
   (mapcar (ap list @2 @1) '((1 2) (a b)))   ->   ((2 1) (b a))
 .brev
 
-.coNP Macros @ opip and @ oand
+.coNP Macros @, opip @, oand @ lopip and @ loand
 .synb
 .mets (opip << clause *)
 .mets (oand << clause *)
+.mets (lopip << clause *)
+.mets (loand << clause *)
 .syne
 .desc
 The
@@ -59102,6 +59104,26 @@ or the respective dot notations, forms which invoke any of the
 .code do
 family of operators, as well as any atom forms.
 
+The
+.code lopip
+and
+.code loand
+operators are similar to, respectively,
+.code opip
+and
+.codn oand ,
+except that they insert the implicit argument as the leftmost
+argument.  For these macros, the above specification of what transformations
+are applied to the arguments is modified as follows:
+
+.verb
+  ;; other compound forms are transformed like this:
+
+  (function ...) -> (lop function ...)
+  (operator ...) -> (ldo operator ...)
+  (macro ...)    -> (ldo macro ...)
+.brev
+
 When a
 .code let
 or
@@ -59263,9 +59285,10 @@ as well as, implicitly, the value
 .code @1
 coming from the previous element,
 
-.coNP Macro @ flow
+.coNP Macros @ flow and @ lflow
 .synb
 .mets (flow < form << opip-arg *)
+.mets (lflow < form << lopip-arg *)
 .syne
 .desc
 The
@@ -59282,10 +59305,19 @@ arguments follow the semantics of the
 .code opip
 macro.
 
-The following equivalence holds:
+The same requirements apply to
+.codn lflow ,
+except that it is related to the
+.code lopip
+macro which inserts the implicit argument into the
+leftmost position.
+
+
+The following equivalences hold:
 
 .verb
-  (flow x ...)  <-->  [(opip ...) x]
+  (flow x ...)   <-->  [(opip ...) x]
+  (lflow x ...)  <-->  [(lopip ...) x]
 .brev
 
 That is to say,
@@ -59293,19 +59325,28 @@ That is to say,
 is equivalent to the application of an
 .codn opip -generated
 function to the value of
-.metn form .
+.metn form ,
+and likewise
+.code lflow
+is equivalent to the application of a
+.codn lopip -generated
+function.
 
 Note: if there are no
 .meta opip-arg
+or
+.meta lopip-arg
 arguments, then
 .code flow
 evaluates the
 .code x
 argument and returns
 .codn nil ;
-which follows from the behavior of
+which follows from the behavior of the
 .code opip
-when that operator is invoked with no arguments.
+and
+.code lopip
+macros, when those are invoked with no arguments.
 
 .TP* Examples:
 
@@ -59313,6 +59354,10 @@ when that operator is invoked with no arguments.
   (flow 1 (+ 2) (* 3) (cons 0)) -> (0 . 9)
 
   (flow "abc" (upcase-str) (regsub #/B/ "ZTE")) -> "AZTEC"
+
+  (flow 1 (- 10)) -> 9
+
+  (lflow 10 (- 1)) -> 9
 .brev
 
 .coNP Macro @ ret