diff --git a/src/examples/pebblisp.pbl b/src/examples/pebblisp.pbl
index 026c36d..0f54b0d 100644
--- a/src/examples/pebblisp.pbl
+++ b/src/examples/pebblisp.pbl
@@ -10,8 +10,12 @@
 (def bold "")
 (def reset "")
 
+(def esc (ch 27))
+
 (def nl (ch 10))
 
+(def first (fn (list) (at 0 list)))
+
 (def up "..")
 (def ~ (env "HOME"))
 
@@ -28,10 +32,23 @@
 
 (def clock (fn (ti) (cat (hour ti) ":" (zero ti.minute) ":" (zero ti.sec))))
 
+(struct Alias (name value))
+(def aliases (
+  (Alias "ls" "ls --color")
+))
+
+(def preprocess (fn (text) (
+  (def matches (fil (fn (a) (= text a.name)) aliases))
+  (def match (first matches))
+  (if (iserr match) text match.value)
+)))
+
 (def prompt (fn (a) (
   (def ti (time))
+  (def d (cwd))
 
   (cat nl
-    bold red "[sage] " blue (clock) " " reset cyan (cwd) nl
+    esc "]0; " d (ch 7)
+    bold red "[sage] " blue (clock) " " reset cyan d nl
     bold green "pebblisp ~> " reset)
 )))
diff --git a/src/pebblisp.c b/src/pebblisp.c
index 6dc4f8c..cf78b04 100644
--- a/src/pebblisp.c
+++ b/src/pebblisp.c
@@ -611,6 +611,15 @@ char* getPrompt(struct Environment* env)
     return ret;
 }
 
+char* preprocess(char* buf, struct Environment* env)
+{
+    Object lambda = fetchFromEnvironment("preprocess", env);
+    Object buffer = nullTerminated(buf);
+    Object s = listEvalLambda(&lambda, &buffer, 2, env);
+    size_t length;
+    return stringObj(&s, &length);
+}
+
 void repl(struct Environment* env)
 {
     char* buf;
@@ -621,12 +630,19 @@ void repl(struct Environment* env)
             free(buf);
             break;
         }
+        buf = preprocess(buf, env);
         if (buf[0] == '\0') {
             free(buf);
             continue;
         }
         add_history(buf);
-        if ((buf[0] == 'c' && buf[1] == 'd') || (buf[0] == '?' && (buf[1] == ' ' || buf[1] == '\0'))) {
+        if ((buf[0] == 'c' && buf[1] == 'd')) {
+            char* oldBuf = buf;
+            buf = malloc(sizeof(char) * strlen(buf + 6));
+            sprintf(buf, "(cd \"%s\")", oldBuf + 3);
+            free(oldBuf);
+        }
+        if ((buf[0] == '?' && (buf[1] == ' ' || buf[1] == '\0'))) {
             char* oldBuf = buf;
             buf = malloc(sizeof(char) * strlen(buf + 3));
             sprintf(buf, "(%s)", oldBuf);
@@ -705,6 +721,8 @@ int main(int argc, const char* argv[])
 
     Object o = parseEval("(def prompt \"pebblisp::> \")", &env);
     cleanObject(&o);
+    o = parseEval("(def preprocess (fn (text) (text)))", &env);
+    cleanObject(&o);
 
     const char* const home = getenv("HOME");
     char config[strlen(home) + 15];