From d67e97e6991fe2d6c8414feda7d72f0ee24f0a9f Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Tue, 29 Dec 2020 00:26:21 -0800
Subject: shuffle/nshuffle: take optional random state argument.

* eval.c (eval_init): Register shuffle and nshuffle as
two-argument functions with optional argument.

* lib.c (nshuffle): Take random-state argument, defaulting to
value of random_state special variable.
(shuffle): Take random-state argument, pass down to nshuffle.

* lib.h (shuffle, nshuffle): Declarations updated.

* txr.1: Updated.
---
 eval.c | 4 ++--
 lib.c  | 8 ++++----
 lib.h  | 4 ++--
 txr.1  | 8 +++++---
 4 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/eval.c b/eval.c
index aaf34aaf..a19524a6 100644
--- a/eval.c
+++ b/eval.c
@@ -6927,9 +6927,9 @@ void eval_init(void)
   reg_fun(intern(lit("nsort"), user_package), func_n3o(nsort, 1));
   reg_fun(intern(lit("sort"), user_package),
           func_n3o(if3(opt_compat && opt_compat <= 237, nsort, sort), 1));
-  reg_fun(intern(lit("nshuffle"), user_package), func_n1(nshuffle));
+  reg_fun(intern(lit("nshuffle"), user_package), func_n2o(nshuffle, 1));
   reg_fun(intern(lit("shuffle"), user_package),
-          func_n1(if3(opt_compat && opt_compat <= 237, nshuffle, shuffle)));
+          func_n2o(if3(opt_compat && opt_compat <= 237, nshuffle, shuffle), 1));
   reg_fun(intern(lit("find"), user_package), func_n4o(find, 2));
   reg_fun(intern(lit("rfind"), user_package), func_n4o(rfind, 2));
   reg_fun(intern(lit("find-if"), user_package), func_n3o(find_if, 2));
diff --git a/lib.c b/lib.c
index b3873c95..462e19a8 100644
--- a/lib.c
+++ b/lib.c
@@ -9653,7 +9653,7 @@ val sort(val seq, val lessfun, val keyfun)
   abort();
 }
 
-val nshuffle(val seq)
+val nshuffle(val seq, val randstate)
 {
   seq_info_t si = seq_info(seq);
 
@@ -9673,7 +9673,7 @@ val nshuffle(val seq)
   case SEQ_VECLIKE:
   case SEQ_HASHLIKE:
     {
-      val rs = random_state;
+      val rs = default_arg(randstate, random_state);
       val n = length(seq);
       val i;
 
@@ -9696,10 +9696,10 @@ val nshuffle(val seq)
   abort();
 }
 
-val shuffle(val seq)
+val shuffle(val seq, val randstate)
 {
   if (seqp(seq))
-    return nshuffle(copy(seq));
+    return nshuffle(copy(seq), randstate);
   type_mismatch(lit("nshuffle: ~s is not a sequence"), seq, nao);
 }
 
diff --git a/lib.h b/lib.h
index 535c2c45..c1951a88 100644
--- a/lib.h
+++ b/lib.h
@@ -1129,8 +1129,8 @@ val interpose(val sep, val seq);
 val merge(val list1, val list2, val lessfun, val keyfun);
 val nsort(val seq, val lessfun, val keyfun);
 val sort(val seq, val lessfun, val keyfun);
-val nshuffle(val seq);
-val shuffle(val seq);
+val nshuffle(val seq, val randstate);
+val shuffle(val seq, val randstate);
 val multi_sort(val lists, val funcs, val key_funcs);
 val sort_group(val seq, val keyfun, val lessfun);
 val unique(val seq, val keyfun, struct args *hashv_args);
diff --git a/txr.1 b/txr.1
index e287c8bb..1829471c 100644
--- a/txr.1
+++ b/txr.1
@@ -33727,8 +33727,8 @@ in the APL language.
 
 .coNP Functions @ shuffle and @ nshuffle
 .synb
-.mets (shuffle << sequence )
-.mets (nshuffle << sequence )
+.mets (shuffle < sequence <> [ random-state ])
+.mets (nshuffle < sequence <> [ random-state ])
 .syne
 .desc
 The
@@ -33745,7 +33745,9 @@ itself.
 
 The rearrangement depends on pseudo-random numbers obtained from the
 .code rand
-function.
+function. The
+.meta random-state
+argument, if present, is passed to that function.
 
 The
 .code nshuffle
-- 
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