tinylisp is, in its essence, a very stripped-down version of Lisp, as the name suggests. It was made by @DLosc for an "interpret this language" challenge, which can be found here. It features a small amount of builtins, which can be used to create practically anything.
What tips do you have for golfing (creating the shortest program possible) in tinylisp? This question is looking for tips to golf specifically in tinylisp, not general tips that can be applied to any language.