From cb4b820893b2cc48a70f2a2f0d70863fb191d7aa Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sun, 2 Mar 2014 22:04:16 -0800
Subject: * eval.c (make_env_intrinsic): New static function. (eval_init):
 Register new intrinsics make-env, env-fbind and env-vbind.

* txr.1: Documented.
---
 ChangeLog |  7 +++++++
 eval.c    | 15 +++++++++++++++
 txr.1     | 43 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 65 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index d20328c5..a4b3a790 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-03-02  Kaz Kylheku  <kaz@kylheku.com>
+
+	* eval.c (make_env_intrinsic): New static function.
+	(eval_init): Register new intrinsics make-env, env-fbind and env-vbind.
+	
+	* txr.1: Documented.
+
 2014-03-02  Kaz Kylheku  <kaz@kylheku.com>
 
 	Version 83
diff --git a/eval.c b/eval.c
index be60544b..7936da92 100644
--- a/eval.c
+++ b/eval.c
@@ -100,6 +100,18 @@ val make_env(val vbindings, val fbindings, val up_env)
   return env;
 }
 
+/*
+ * Wrapper for performance reasons: don't make make_env
+ * process default arguments.
+ */
+static val make_env_intrinsic(val vbindings, val fbindings, val up_env)
+{
+  vbindings = default_bool_arg(vbindings);
+  fbindings = default_bool_arg(fbindings);
+  up_env = default_bool_arg(up_env);
+  return make_env(vbindings, fbindings, up_env);
+}
+
 val env_fbind(val env, val sym, val fun)
 {
   val cell;
@@ -3309,6 +3321,9 @@ void eval_init(void)
           func_n2o(macroexpand_1, 1));
   reg_fun(intern(lit("macroexpand"), user_package),
           func_n2o(macroexpand, 1));
+  reg_fun(intern(lit("make-env"), user_package), func_n3o(make_env_intrinsic, 0));
+  reg_fun(intern(lit("env-fbind"), user_package), func_n3(env_fbind));
+  reg_fun(intern(lit("env-vbind"), user_package), func_n3(env_vbind));
   reg_fun(intern(lit("chain"), user_package), func_n0v(chainv));
   reg_fun(intern(lit("andf"), user_package), func_n0v(andv));
   reg_fun(intern(lit("orf"), user_package), func_n0v(orv));
diff --git a/txr.1 b/txr.1
index 853a6988..173d2d41 100644
--- a/txr.1
+++ b/txr.1
@@ -5802,6 +5802,49 @@ resolving the function and variable references encountered in the expression.
 The object nil can be specified as an environment, in which case the evaluation
 takes place in the global environment.
 
+See also: the make-env function.
+
+.SS Function make-env
+
+.TP
+Syntax:
+
+  (make-env [<variable-bindings> [<function-bindings> [<next-env>]]])
+
+.TP
+Description:
+
+The make-env function creates an environment object suitable as the <env> parameter.
+
+The <variable-bindings> and <function-bindings> parameters, if specified,
+should be association lists, mapping symbols to objects.  The objects in
+<function-bindings> should be functions, or objects callable as functions.
+
+The <next-env> argument, if specified, should be an environment. 
+
+Note: bindings can also be added to an environment usign the env-vbind
+and env-fbind functions.
+
+.SS Functions env-vbind and env-fbind
+
+.TP
+Syntax:
+
+  (env-vbind <env> <symbol> <value>)
+  (env-fbind <env> <symbol> <value>)
+
+.TP
+Description:
+
+These functions bind a symbol to a value in either the function or variable space
+of environment <env>.
+
+Values established in the function space should be functions or objects that
+can be used as functions such as lists, strings, arrays or hashes.
+
+If <symbol> already exists in the environment, in the given space, then its
+value is updated with <value>.
+
 .SH MUTATION
 
 .SS Operators inc, dec, set, push, pop, flip and del
-- 
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