From 3169070063b2cb877200117ebb384269d73bcb93 Mon Sep 17 00:00:00 2001
From: Joel Martin <github@martintribe.org>
Date: Mon, 24 Mar 2014 16:32:24 -0500
Subject: Current state of mal for Clojure West lighting talk.

---
 php/step2_eval.php | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 php/step2_eval.php

(limited to 'php/step2_eval.php')

diff --git a/php/step2_eval.php b/php/step2_eval.php
new file mode 100644
index 0000000..c9c3562
--- /dev/null
+++ b/php/step2_eval.php
@@ -0,0 +1,77 @@
+<?php
+
+require_once 'readline.php';
+require_once 'types.php';
+require_once 'reader.php';
+
+// read
+function READ($str) {
+    return read_str($str);
+}
+
+// eval
+function eval_ast($ast, $env) {
+    if (symbol_Q($ast)) {
+        return $env[$ast->value];
+    } elseif (list_Q($ast) || vector_Q($ast)) {
+        if (list_Q($ast)) {
+            $el = new_list();
+        } else {
+            $el = new_vector();
+        }
+        foreach ($ast as $a) { $el[] = MAL_EVAL($a, $env); }
+        return $el;
+    } elseif (hash_map_Q($ast)) {
+        $new_hm = new_hash_map();
+        foreach (array_keys($ast->getArrayCopy()) as $key) {
+            $new_hm[$key] = MAL_EVAL($ast[$key], $env);
+        }
+        return $new_hm;
+    } else {
+        return $ast;
+    }
+}
+
+function MAL_EVAL($ast, $env) {
+    if (!list_Q($ast)) {
+        return eval_ast($ast, $env);
+    }
+
+    // apply list
+    $el = eval_ast($ast, $env);
+    $f = $el[0];
+    return call_user_func_array($f, array_slice($el->getArrayCopy(), 1));
+}
+
+// print
+function MAL_PRINT($exp) {
+    return _pr_str($exp, True) . "\n";
+}
+
+// repl
+$repl_env = array();
+function rep($str) {
+    global $repl_env;
+    return MAL_PRINT(MAL_EVAL(READ($str), $repl_env));
+}
+$repl_env['+'] = function ($a, $b) { return intval($a + $b,10); };
+$repl_env['-'] = function ($a, $b) { return intval($a - $b,10); };
+$repl_env['*'] = function ($a, $b) { return intval($a * $b,10); };
+$repl_env['/'] = function ($a, $b) { return intval($a / $b,10); };
+
+do {
+    try {
+        $line = mal_readline("user> ");
+        if ($line === NULL) { break; }
+        if ($line !== "") {
+            print(rep($line));
+        }
+    } catch (BlankException $e) {
+        continue;
+    } catch (Exception $e) {
+        echo "Error: " . $e->getMessage() . "\n";
+        echo $e->getTraceAsString() . "\n";
+    }
+} while (true);
+
+?> 
-- 
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