Merge branch 'master' into gh-pages

Conflicts:
	.gitignore

15 files changed, 139 insertions, 69 deletions

diff --git a/php/Makefile b/php/Makefile
index 9b91421..659e89c 100644
--- a/php/Makefile
+++ b/php/Makefile
@@ -2,7 +2,7 @@
 TESTS =
 
 SOURCES_BASE = readline.php types.php reader.php printer.php
-SOURCES_LISP = env.php core.php stepA_more.php
+SOURCES_LISP = env.php core.php stepA_mal.php
 SOURCES = $(SOURCES_BASE) $(SOURCES_LISP)
 
 .PHONY: stats tests $(TESTS)
diff --git a/php/core.php b/php/core.php
index 4cb4667..96129b1 100644
--- a/php/core.php
+++ b/php/core.php
@@ -97,7 +97,11 @@ function concat() {
 }
 
 function nth($seq, $idx) {
-    return $seq[$idx];
+    if ($idx < $seq->count()) {
+        return $seq[$idx];
+    } else {
+        throw new Exception("nth: index out of range");
+    }
 }
 
 function first($seq) {
@@ -177,6 +181,8 @@ $core_ns = array(
     'false?'=> function ($a) { return _false_Q($a); },
     'symbol'=> function () { return call_user_func_array('_symbol', func_get_args()); },
     'symbol?'=> function ($a) { return _symbol_Q($a); },
+    'keyword'=> function () { return call_user_func_array('_keyword', func_get_args()); },
+    'keyword?'=> function ($a) { return _keyword_Q($a); },
 
     'string?'=> function ($a) { return _string_Q($a); },
     'pr-str'=> function () { return call_user_func_array('pr_str', func_get_args()); },
diff --git a/php/env.php b/php/env.php
index 61bedaf..a660d3b 100644
--- a/php/env.php
+++ b/php/env.php
@@ -31,7 +31,7 @@ class Env {
         }
     }
     public function find($key) {
-        if (array_key_exists($key, $this->data)) {
+        if (array_key_exists($key->value, $this->data)) {
             return $this;
         } elseif ($this->outer) {
             return $this->outer->find($key);
@@ -40,15 +40,15 @@ class Env {
         }
     }
     public function set($key, $value) {
-        $this->data[$key] = $value;
+        $this->data[$key->value] = $value;
         return $value;
     }
     public function get($key) {
         $env = $this->find($key);
         if (!$env) {
-            throw new Exception("'" . $key . "' not found");
+            throw new Exception("'" . $key->value . "' not found");
         } else {
-            return $env->data[$key];
+            return $env->data[$key->value];
         }
     }
 }
diff --git a/php/printer.php b/php/printer.php
index 3839931..130d31b 100644
--- a/php/printer.php
+++ b/php/printer.php
@@ -23,7 +23,9 @@ function _pr_str($obj, $print_readably=True) {
         }
         return "{" . implode(" ", $ret) . "}";
     } elseif (is_string($obj)) {
-        if ($print_readably) {
+        if (strpos($obj, chr(0x7f)) === 0) {
+            return ":".substr($obj,1);
+        } elseif ($print_readably) {
             $obj = preg_replace('/"/', '\\"', preg_replace('/\\\\/', '\\\\\\\\', $obj));
             return '"' . $obj . '"';
         } else {
diff --git a/php/reader.php b/php/reader.php
index 83e0cff..ed9063f 100644
--- a/php/reader.php
+++ b/php/reader.php
@@ -40,6 +40,8 @@ function read_atom($reader) {
         $str = substr($token, 1, -1);
         $str = preg_replace('/\\\\"/', '"', $str);
         return $str;
+    } elseif ($token[0] === ":") {
+        return _keyword(substr($token,1));
     } elseif ($token === "nil") {
         return NULL;
     } elseif ($token === "true") {
diff --git a/php/step3_env.php b/php/step3_env.php
index 6585fe7..a31c298 100644
--- a/php/step3_env.php
+++ b/php/step3_env.php
@@ -14,7 +14,7 @@ function READ($str) {
 // eval
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -46,12 +46,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         return MAL_EVAL($ast[2], $let_env);
     default:
@@ -73,10 +73,10 @@ function rep($str) {
     return MAL_PRINT(MAL_EVAL(READ($str), $repl_env));
 }
 
-$repl_env->set('+', function ($a, $b) { return intval($a + $b,10); });
-$repl_env->set('-', function ($a, $b) { return intval($a - $b,10); });
-$repl_env->set('*', function ($a, $b) { return intval($a * $b,10); });
-$repl_env->set('/', function ($a, $b) { return intval($a / $b,10); });
+$repl_env->set(_symbol('+'), function ($a, $b) { return intval($a + $b,10); });
+$repl_env->set(_symbol('-'), function ($a, $b) { return intval($a - $b,10); });
+$repl_env->set(_symbol('*'), function ($a, $b) { return intval($a * $b,10); });
+$repl_env->set(_symbol('/'), function ($a, $b) { return intval($a / $b,10); });
 
 // repl loop
 do {
diff --git a/php/step4_if_fn_do.php b/php/step4_if_fn_do.php
index 1e88c6a..7266261 100644
--- a/php/step4_if_fn_do.php
+++ b/php/step4_if_fn_do.php
@@ -15,7 +15,7 @@ function READ($str) {
 // eval
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -47,12 +47,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         return MAL_EVAL($ast[2], $let_env);
     case "do":
@@ -93,7 +93,7 @@ function rep($str) {
 
 // core.php: defined using PHP
 foreach ($core_ns as $k=>$v) {
-    $repl_env->set($k, _function($v));
+    $repl_env->set(_symbol($k), _function($v));
 }
 
 // core.mal: defined using the language itself
diff --git a/php/step5_tco.php b/php/step5_tco.php
index 88557b5..a3785cf 100644
--- a/php/step5_tco.php
+++ b/php/step5_tco.php
@@ -15,7 +15,7 @@ function READ($str) {
 // eval
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -49,12 +49,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         $ast = $ast[2];
         $env = $let_env;
@@ -105,7 +105,7 @@ function rep($str) {
 
 // core.php: defined using PHP
 foreach ($core_ns as $k=>$v) {
-    $repl_env->set($k, _function($v));
+    $repl_env->set(_symbol($k), _function($v));
 }
 
 // core.mal: defined using the language itself
diff --git a/php/step6_file.php b/php/step6_file.php
index 1e83c28..a27acb8 100644
--- a/php/step6_file.php
+++ b/php/step6_file.php
@@ -15,7 +15,7 @@ function READ($str) {
 // eval
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -49,12 +49,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         $ast = $ast[2];
         $env = $let_env;
@@ -105,16 +105,16 @@ function rep($str) {
 
 // core.php: defined using PHP
 foreach ($core_ns as $k=>$v) {
-    $repl_env->set($k, _function($v));
+    $repl_env->set(_symbol($k), _function($v));
 }
-$repl_env->set('eval', _function(function($ast) {
+$repl_env->set(_symbol('eval'), _function(function($ast) {
     global $repl_env; return MAL_EVAL($ast, $repl_env);
 }));
 $_argv = _list();
 for ($i=2; $i < count($argv); $i++) {
     $_argv->append($argv[$i]);
 }
-$repl_env->set('*ARGV*', $_argv);
+$repl_env->set(_symbol('*ARGV*'), $_argv);
 
 // core.mal: defined using the language itself
 rep("(def! not (fn* (a) (if a false true)))");
diff --git a/php/step7_quote.php b/php/step7_quote.php
index 07d3d2a..37903d0 100644
--- a/php/step7_quote.php
+++ b/php/step7_quote.php
@@ -34,7 +34,7 @@ function quasiquote($ast) {
 
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -68,12 +68,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         $ast = $ast[2];
         $env = $let_env;
@@ -129,16 +129,16 @@ function rep($str) {
 
 // core.php: defined using PHP
 foreach ($core_ns as $k=>$v) {
-    $repl_env->set($k, _function($v));
+    $repl_env->set(_symbol($k), _function($v));
 }
-$repl_env->set('eval', _function(function($ast) {
+$repl_env->set(_symbol('eval'), _function(function($ast) {
     global $repl_env; return MAL_EVAL($ast, $repl_env);
 }));
 $_argv = _list();
 for ($i=2; $i < count($argv); $i++) {
     $_argv->append($argv[$i]);
 }
-$repl_env->set('*ARGV*', $_argv);
+$repl_env->set(_symbol('*ARGV*'), $_argv);
 
 // core.mal: defined using the language itself
 rep("(def! not (fn* (a) (if a false true)))");
diff --git a/php/step8_macros.php b/php/step8_macros.php
index aacf33e..c7e0175 100644
--- a/php/step8_macros.php
+++ b/php/step8_macros.php
@@ -35,13 +35,13 @@ function quasiquote($ast) {
 function is_macro_call($ast, $env) {
     return is_pair($ast) &&
            _symbol_Q($ast[0]) &&
-           $env->find($ast[0]->value) &&
-           $env->get($ast[0]->value)->ismacro;
+           $env->find($ast[0]) &&
+           $env->get($ast[0])->ismacro;
 }
 
 function macroexpand($ast, $env) {
     while (is_macro_call($ast, $env)) {
-        $mac = $env->get($ast[0]->value);
+        $mac = $env->get($ast[0]);
         $args = array_slice($ast->getArrayCopy(),1);
         $ast = $mac->apply($args);
     }
@@ -50,7 +50,7 @@ function macroexpand($ast, $env) {
 
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -87,12 +87,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         $ast = $ast[2];
         $env = $let_env;
@@ -105,7 +105,7 @@ function MAL_EVAL($ast, $env) {
     case "defmacro!":
         $func = MAL_EVAL($ast[2], $env);
         $func->ismacro = true;
-        return $env->set($ast[1]->value, $func);
+        return $env->set($ast[1], $func);
     case "macroexpand":
         return macroexpand($ast[1], $env);
     case "do":
@@ -154,16 +154,16 @@ function rep($str) {
 
 // core.php: defined using PHP
 foreach ($core_ns as $k=>$v) {
-    $repl_env->set($k, _function($v));
+    $repl_env->set(_symbol($k), _function($v));
 }
-$repl_env->set('eval', _function(function($ast) {
+$repl_env->set(_symbol('eval'), _function(function($ast) {
     global $repl_env; return MAL_EVAL($ast, $repl_env);
 }));
 $_argv = _list();
 for ($i=2; $i < count($argv); $i++) {
     $_argv->append($argv[$i]);
 }
-$repl_env->set('*ARGV*', $_argv);
+$repl_env->set(_symbol('*ARGV*'), $_argv);
 
 // core.mal: defined using the language itself
 rep("(def! not (fn* (a) (if a false true)))");
diff --git a/php/stepA_more.php b/php/step9_try.php
index f38656f..0470763 100644
--- a/php/stepA_more.php
+++ b/php/step9_try.php
@@ -35,13 +35,13 @@ function quasiquote($ast) {
 function is_macro_call($ast, $env) {
     return is_pair($ast) &&
            _symbol_Q($ast[0]) &&
-           $env->find($ast[0]->value) &&
-           $env->get($ast[0]->value)->ismacro;
+           $env->find($ast[0]) &&
+           $env->get($ast[0])->ismacro;
 }
 
 function macroexpand($ast, $env) {
     while (is_macro_call($ast, $env)) {
-        $mac = $env->get($ast[0]->value);
+        $mac = $env->get($ast[0]);
         $args = array_slice($ast->getArrayCopy(),1);
         $ast = $mac->apply($args);
     }
@@ -50,7 +50,7 @@ function macroexpand($ast, $env) {
 
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -87,12 +87,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         $ast = $ast[2];
         $env = $let_env;
@@ -105,11 +105,9 @@ function MAL_EVAL($ast, $env) {
     case "defmacro!":
         $func = MAL_EVAL($ast[2], $env);
         $func->ismacro = true;
-        return $env->set($ast[1]->value, $func);
+        return $env->set($ast[1], $func);
     case "macroexpand":
         return macroexpand($ast[1], $env);
-    case "php*":
-        return eval($ast[1]);
     case "try*":
         $a1 = $ast[1];
         $a2 = $ast[2];
@@ -174,19 +172,18 @@ function rep($str) {
 
 // core.php: defined using PHP
 foreach ($core_ns as $k=>$v) {
-    $repl_env->set($k, _function($v));
+    $repl_env->set(_symbol($k), _function($v));
 }
-$repl_env->set('eval', _function(function($ast) {
+$repl_env->set(_symbol('eval'), _function(function($ast) {
     global $repl_env; return MAL_EVAL($ast, $repl_env);
 }));
 $_argv = _list();
 for ($i=2; $i < count($argv); $i++) {
     $_argv->append($argv[$i]);
 }
-$repl_env->set('*ARGV*', $_argv);
+$repl_env->set(_symbol('*ARGV*'), $_argv);
 
 // core.mal: defined using the language itself
-rep("(def! *host-language* \"php\")");
 rep("(def! not (fn* (a) (if a false true)))");
 rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))");
 rep("(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))");
@@ -198,7 +195,6 @@ if (count($argv) > 1) {
 }
 
 // repl loop
-rep("(println (str \"Mal [\" *host-language* \"]\"))");
 do {
     try {
         $line = mal_readline("user> ");
diff --git a/php/step9_interop.php b/php/stepA_mal.php
index d4a59c7..1dc3b04 100644
--- a/php/step9_interop.php
+++ b/php/stepA_mal.php
@@ -35,13 +35,13 @@ function quasiquote($ast) {
 function is_macro_call($ast, $env) {
     return is_pair($ast) &&
            _symbol_Q($ast[0]) &&
-           $env->find($ast[0]->value) &&
-           $env->get($ast[0]->value)->ismacro;
+           $env->find($ast[0]) &&
+           $env->get($ast[0])->ismacro;
 }
 
 function macroexpand($ast, $env) {
     while (is_macro_call($ast, $env)) {
-        $mac = $env->get($ast[0]->value);
+        $mac = $env->get($ast[0]);
         $args = array_slice($ast->getArrayCopy(),1);
         $ast = $mac->apply($args);
     }
@@ -50,7 +50,7 @@ function macroexpand($ast, $env) {
 
 function eval_ast($ast, $env) {
     if (_symbol_Q($ast)) {
-        return $env->get($ast->value);
+        return $env->get($ast);
     } elseif (_sequential_Q($ast)) {
         if (_list_Q($ast)) {
             $el = _list();
@@ -87,12 +87,12 @@ function MAL_EVAL($ast, $env) {
     switch ($a0v) {
     case "def!":
         $res = MAL_EVAL($ast[2], $env);
-        return $env->set($ast[1]->value, $res);
+        return $env->set($ast[1], $res);
     case "let*":
         $a1 = $ast[1];
         $let_env = new Env($env);
         for ($i=0; $i < count($a1); $i+=2) {
-            $let_env->set($a1[$i]->value, MAL_EVAL($a1[$i+1], $let_env));
+            $let_env->set($a1[$i], MAL_EVAL($a1[$i+1], $let_env));
         }
         $ast = $ast[2];
         $env = $let_env;
@@ -105,11 +105,41 @@ function MAL_EVAL($ast, $env) {
     case "defmacro!":
         $func = MAL_EVAL($ast[2], $env);
         $func->ismacro = true;
-        return $env->set($ast[1]->value, $func);
+        return $env->set($ast[1], $func);
     case "macroexpand":
         return macroexpand($ast[1], $env);
     case "php*":
-        return eval($ast[1]);
+        $res = eval($ast[1]);
+        switch (gettype($res)) {
+        case "array":
+            if ($res !== array_values($res)) {
+                $new_res = _hash_map();
+                $new_res->exchangeArray($res);
+                return $new_res;
+            } else {
+                return call_user_func_array('_list', $res);
+            }
+        default:
+            return $res;
+        }
+    case "try*":
+        $a1 = $ast[1];
+        $a2 = $ast[2];
+        if ($a2[0]->value === "catch*") {
+            try {
+                return MAL_EVAL($a1, $env);
+            } catch (Error $e) {
+                $catch_env = new Env($env, array($a2[1]),
+                                            array($e->obj));
+                return MAL_EVAL($a2[2], $catch_env);
+            } catch (Exception $e) {
+                $catch_env = new Env($env, array($a2[1]),
+                                            array($e->getMessage()));
+                return MAL_EVAL($a2[2], $catch_env);
+            }
+        } else {
+            return MAL_EVAL($a1, $env);
+        }
     case "do":
         eval_ast($ast->slice(1, -1), $env);
         $ast = $ast[count($ast)-1];
@@ -156,18 +186,19 @@ function rep($str) {
 
 // core.php: defined using PHP
 foreach ($core_ns as $k=>$v) {
-    $repl_env->set($k, _function($v));
+    $repl_env->set(_symbol($k), _function($v));
 }
-$repl_env->set('eval', _function(function($ast) {
+$repl_env->set(_symbol('eval'), _function(function($ast) {
     global $repl_env; return MAL_EVAL($ast, $repl_env);
 }));
 $_argv = _list();
 for ($i=2; $i < count($argv); $i++) {
     $_argv->append($argv[$i]);
 }
-$repl_env->set('*ARGV*', $_argv);
+$repl_env->set(_symbol('*ARGV*'), $_argv);
 
 // core.mal: defined using the language itself
+rep("(def! *host-language* \"php\")");
 rep("(def! not (fn* (a) (if a false true)))");
 rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \")\")))))");
 rep("(defmacro! cond (fn* (& xs) (if (> (count xs) 0) (list 'if (first xs) (if (> (count xs) 1) (nth xs 1) (throw \"odd number of forms to cond\")) (cons 'cond (rest (rest xs)))))))");
@@ -179,6 +210,7 @@ if (count($argv) > 1) {
 }
 
 // repl loop
+rep("(println (str \"Mal [\" *host-language* \"]\"))");
 do {
     try {
         $line = mal_readline("user> ");
diff --git a/php/tests/stepA_mal.mal b/php/tests/stepA_mal.mal
new file mode 100644
index 0000000..15f8a94
--- /dev/null
+++ b/php/tests/stepA_mal.mal
@@ -0,0 +1,25 @@
+;; Testing basic php interop
+
+(php* "return 7;")
+;=>7
+
+(php* "return '7';")
+;=>"7"
+
+(php* "return array(7,8,9);")
+;=>(7 8 9)
+
+(php* "return array(\"abc\" => 789);")
+;=>{"abc" 789}
+
+(php* "print \"hello\n\";")
+; hello
+;=>nil
+
+(php* "global $foo; $foo=8;")
+(php* "global $foo; return $foo;")
+;=>8
+
+(php* "global $f; $f = function($v) { return 1+$v; };")
+(php* "global $f; return array_map($f, array(1,2,3));")
+;=>(2 3 4)
diff --git a/php/types.php b/php/types.php
index e3df3ac..fa87197 100644
--- a/php/types.php
+++ b/php/types.php
@@ -53,6 +53,13 @@ class SymbolClass {
 function _symbol($name) { return new SymbolClass($name); }
 function _symbol_Q($obj) { return ($obj instanceof SymbolClass); }
 
+// Keywords
+function _keyword($name) { return chr(0x7f).$name; }
+function _keyword_Q($obj) {
+    return is_string($obj) && strpos($obj, chr(0x7f)) === 0;
+}
+
+
 
 // Functions
 class FunctionClass {