From 263934fc9744e7bc7129d244ff6340de90468052 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 24 Feb 2022 00:25:23 -0800
Subject: opip: pass through forms in the op family.

* stdlib/op.tl (sys:opip-expand): Add op, do, lop, ldo, ap,
ip, ado, ido, ret and aret to the operators whose forms are
passed through untransformed. This is important because it
lets us override the implicit (op ...) and (do ...) chosen
by the expander. When a pipeline element produces a list, for
instance, we want to be able to use (ap ...) in the next
element to spread the list into arguments.

* tests/012/op.tl: Add bellied numbers test case.

* txr.1: Documented.
---
 stdlib/op.tl    |  2 +-
 tests/012/op.tl |  6 ++++++
 txr.1           | 25 +++++++++++++++++++++----
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/stdlib/op.tl b/stdlib/op.tl
index 2754ca0d..1f242745 100644
--- a/stdlib/op.tl
+++ b/stdlib/op.tl
@@ -221,7 +221,7 @@
     (if (atom c)
       c
       (let ((sym (car c)))
-        (if (member sym '(dwim uref qref))
+        (if (member sym '(dwim uref qref op do lop ldo ap ip ado ido ret aret))
           c
           (let ((opdo (if (or (special-operator-p (car c))
                               (macro-form-p c e)) 'do 'op)))
diff --git a/tests/012/op.tl b/tests/012/op.tl
index 5a789219..aafe0a28 100644
--- a/tests/012/op.tl
+++ b/tests/012/op.tl
@@ -93,3 +93,9 @@
   [[[[(do do do op list) 1] 2] 3] 4] (1 2 3 4)
   [[[[(do do do op list @1 @@1 @@@1 @@@@1) 1] 2] 3] 4] (4 3 2 1)
   [[[[(do do do op list @@@@1 @@@1 @@1 @1) 1] 2] 3] 4] (1 2 3 4))
+
+(test (flow (range 1000 9999)
+        (keep-if (opip digits (ap > (+ @2 @3) (+ @1 @4))))
+        (partition-if (op neq 1 (- @2 @1)))
+        (find-max-key @1 : len))
+      80)
diff --git a/txr.1 b/txr.1
index 03386c86..b1cf7148 100644
--- a/txr.1
+++ b/txr.1
@@ -56777,16 +56777,31 @@ where the above
 notation denotes the following transformation applied to each argument:
 
 .verb
-  (function ...) -> (op function ...)
-  (operator ...) -> (do operator ...)
-  (macro ...)    -> (do macro ...)
+  ;; these specific form patterns are left untransformed:
+
   (dwim ...)     -> (dwim ...)
   [...]          -> [...]
   (qref ...)     -> (qref ...)
   (uref ...)     -> (uref ...)
+  (op ...)       -> (op ...)
+  (do ...)       -> (do ...)
+  (lop ...)      -> (lop ...)
+  (ldo ...)      -> (ldo ...)
+  (ap ...)       -> (ap ...)
+  (ip ...)       -> (ip ...)
+  (ado ...)      -> (ado ...)
+  (ido ...)      -> (ido ...)
+  (ret ...)      -> (ret ...)
+  (aret ...)     -> (aret ...)
   .slot          -> .slot
   .(method ...)  -> .(method ...)
   atom           -> atom
+
+  ;; other compound forms are transformed like this:
+
+  (function ...) -> (op function ...)
+  (operator ...) -> (do operator ...)
+  (macro ...)    -> (do macro ...)
 .brev
 
 In other words, compound forms whose leftmost symbol is a macro or operator
@@ -56802,7 +56817,9 @@ denoting struct slot access, either explicitly using
 .code uref
 or
 .code qref
-or the respective dot notations, as well as any atom forms.
+or the respective dot notations, forms which invoke any of the
+.code do
+family of operators, as well as any atom forms.
 
 Note: the
 .code opip
-- 
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