From 96a062025a5509b48d1fb0cf48db783229ef40c4 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Wed, 11 Dec 2013 07:32:17 -0800
Subject: * eval.c (symbol_value, boundp, fboundp): New functions. (eval_init):
 New functions registred as intrinsics.

* txr.1: Documented.
---
 ChangeLog |  7 +++++++
 eval.c    | 19 +++++++++++++++++++
 txr.1     | 35 +++++++++++++++++++++++++++++------
 3 files changed, 55 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index c8c49f6d..c42adde9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2013-12-11  Kaz Kylheku  <kaz@kylheku.com>
+
+	* eval.c (symbol_value, boundp, fboundp): New functions.
+	(eval_init): New functions registred as intrinsics.
+
+	* txr.1: Documented.
+
 2013-12-11  Kaz Kylheku  <kaz@kylheku.com>
 
 	* arith.c, hash.c, lib.c, rand.c, stream.c, syslog.c: Removing
diff --git a/eval.c b/eval.c
index 9bb509ef..a14d56d2 100644
--- a/eval.c
+++ b/eval.c
@@ -1903,11 +1903,27 @@ static val lazy_mappendv(val fun, val list_of_lists)
   return lazy_appendv(lazy_mapcarv(fun, list_of_lists));
 }
 
+static val symbol_value(val sym)
+{
+  return cdr(lookup_var(nil, sym));
+}
+
 static val symbol_function(val sym)
 {
   return cdr(lookup_fun(nil, sym));
 }
 
+static val boundp(val sym)
+{
+  return if3(lookup_var(nil, sym), t, nil);
+}
+
+static val fboundp(val sym)
+{
+  return if3(lookup_fun(nil, sym), t,
+             if3(gethash(op_table, sym), t, nil));
+}
+
 static val rangev_func(val env, val lcons)
 {
   cons_bind (from, to_step, env);
@@ -2534,7 +2550,10 @@ void eval_init(void)
   reg_fun(intern(lit("refset"), user_package), func_n3(refset));
   reg_fun(intern(lit("replace"), user_package), func_n4o(replace, 2));
 
+  reg_fun(intern(lit("symbol-value"), user_package), func_n1(symbol_value));
   reg_fun(intern(lit("symbol-function"), user_package), func_n1(symbol_function));
+  reg_fun(intern(lit("boundp"), user_package), func_n1(boundp));
+  reg_fun(intern(lit("fboundp"), user_package), func_n1(fboundp));
   reg_fun(intern(lit("func-get-form"), user_package), func_n1(func_get_form));
   reg_fun(intern(lit("func-get-env"), user_package), func_n1(func_get_env));
   reg_fun(intern(lit("functionp"), user_package), func_n1(functionp));
diff --git a/txr.1 b/txr.1
index 08da5065..329a1431 100644
--- a/txr.1
+++ b/txr.1
@@ -5858,25 +5858,48 @@ Dialect Note:
 A lambda expression is not a function name in TXR Lisp. The 
 syntax (fun (lambda ...)) is invalid.
 
-.SS Function symbol-function
+.SS Functions symbol-function and symbol-value
 
 .TP
 Syntax:
 
   (symbol-function <symbol>)
+  (symbol-value <symbol>)
 
 .TP
 Description:
 
-The symbol-function retrieves the toplevel function binding of the given
-symbol if it has one. If the symbol has no toplevel function binding,
-the value nil is returned.
+The symbol-function retrieves the value of the toplevel function binding of the
+given symbol if it has one: that is, the function object tied to the symbol. If
+the symbol has no toplevel function binding, the value nil is returned.
+
+The symbol-value retrives the value of a toplevel variable, if it exists,
+otherwise nil.
 
 .TP
 Dialect note:
 
-The symbol-function form is currently not an assignable place. Only
-the defun operator defines functions.
+Forms which call symbol-function or symbol-value are currently not an
+assignable place. Only the defun operator defines functions, and the set
+operator modifies variables. There is no way to modify a toplevel variable that
+is shadowed by a lexical variable.
+
+.SS Functions boundp and fboundp
+
+.TP
+Syntax:
+
+  (boundp <symbol>)
+  (fboundp <symbol>)
+
+.TP
+Description:
+
+boundp returns t if the symbol has a variable binding in the toplevel
+environment, otherwise nil.  
+
+Foundp returns t if the symbol has a function binding in the toplevel
+environment, or if it is an operator, otherwise nil.
 
 .SS Function func-get-form
 
-- 
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