From d5e7ea92ffcde75c4401e009c74d63ee70ba9ff2 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Tue, 25 Jun 2019 20:25:51 -0700
Subject: in: allow hash with keyfun and testfun.

* lib.c (in): A simple check and fallthrough lets this
function process hash tables more generally in this function.

* txr.1: Documented.
---
 lib.c |  4 +++-
 txr.1 | 31 ++++++++++++++++++++++++++++---
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/lib.c b/lib.c
index 1d76aa65..40662d29 100644
--- a/lib.c
+++ b/lib.c
@@ -9709,7 +9709,9 @@ val in(val seq, val item, val testfun, val keyfun)
   default:
     switch (si.kind) {
     case SEQ_HASHLIKE:
-      return tnil(gethash_e(self, si.obj, item));
+      if (null_or_missing_p(testfun) && null_or_missing_p(keyfun))
+        return tnil(gethash_e(self, si.obj, item));
+      /* fallthrough */
     case SEQ_LISTLIKE:
     case SEQ_VECLIKE:
       {
diff --git a/txr.1 b/txr.1
index 5164cb85..324ad7d3 100644
--- a/txr.1
+++ b/txr.1
@@ -29748,11 +29748,36 @@ to produce the comparison keys. Without this
 argument, the elements themselves are taken
 as the comparison keys.
 
-If the object being searched is a hash, then the
+If the object being searched is a hash, then if neither of the arguments
 .meta keyfun
-and
+nor
+.meta testfun
+is specified,
+.code in
+performs a hash lookup for
+.codn key ,
+returning
+.code t
+if the key is found,
+.code nil
+otherwise.
+If either of
+.meta keyfun
+or
 .meta testfun
-arguments are ignored.
+is specified, then
+.code in
+performs an exhaustive search of the hash table, as if it were
+a sequence of
+.code cons
+cells whose
+.code car
+fields are keys, and whose
+.code cdr
+keys are values. Thus to search by key, the
+.code car
+function must be specified as
+.metn keyfun .
 
 The
 .code in
-- 
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