Add standard anaphoric macros aif and awhen

src/utils.lisp

@@ -7,13 +7,29 @@
 (defpackage stoe.utils
   (:use :cl)
   (:nicknames :utils)
-  (:export :restartable
+  (:export :it
+           :aif
+           :awhen
+           :restartable
            :eval-repl
            :update-current-time :get-delta-time
            :make-clock :clock-time :clock-delta
            :update-clock :compare-clocks))
 (in-package :stoe.utils)
 
+(defmacro aif (test then else)
+  "Bind the result of evaluating `test' to a variable named `it', as per Paul Graham's On Lisp."
+  `(let ((it ,test))
+     (if it
+         ,then
+         ,else)))
+
+(defmacro awhen (test &body body)
+  "Bind the result of evaluating `test' to a variable named `it', as per Paul Graham's On Lisp."
+  `(let ((it ,test))
+     (when it
+       ,@body)))
+
 (defmacro restartable (unprotected &body body)
   "Provide a Continue restart unless unprotected is t."
   `(if ,unprotected