Implement COND, LET*, and LIST*.

1 files changed, 30 insertions, 0 deletions

diff --git a/cond.lisp b/cond.lisp
new file mode 100644
index 0000000..e5aed02
--- /dev/null
+++ b/cond.lisp
@@ -0,0 +1,30 @@
+(%fset 'list*
+  (%lambda args
+    (if (null (cdr args))
+        (car args)
+        (cons (car args)
+              (apply 'list* (cdr args))))))
+
+(%defmacro let* args
+  (let ((form (car args)))
+    (let ((bindings (car (cdr form)))
+          (body (cdr (cdr form))))
+      (if (null bindings)
+          (list* 'let nil body)
+          (let ((first-binding (car bindings))
+                (rest (cdr bindings)))
+            (list 'let
+                  (list first-binding)
+                  (list* 'let* rest body)))))))
+
+(%defmacro cond args
+  (let* ((form (car args))
+         (clauses (cdr form))
+         (clause (car clauses))
+         (rest (cdr clauses)))
+    (if (null clauses)
+        nil
+        (list 'if
+              (car clause)
+              (cons 'progn (cdr clause))
+              (cons 'cond rest)))))