#+title: Lisp primitives
- tags :: [[file:20200604222651-lisp.org][Lisp]] [[file:20210307152738-programming_languages.org][programming languages]] [[file:20210314131218-dial.org][Dial]] [[file:20210403130721-dial_implementation.org][Dial implementation]]

When implementing a Lisp in particular, the goal should be to express the
totality of the Lisp with only a minimal set of implementation language code.
For example, it wouldn't make a lot of sense to implement =when= in the source
language (say, C) when, if =if= is implemented, it could be expressed as =if=[fn:1].

Primitives include but are not limited to:
- Basic data types
- Any arithmetic
- =lambda= or equivalent
- =if= 
- =cond=
- =list=
- =apply=
- =defmacro=
- =quote=

The rest of a Lisp is simply library code, which can be expressed using all of
the above.

* Footnotes

[fn:1] In fact, it could be expressed like this:
#+begin_src emacs-lisp
; a copy of emacs's own =when= definition
(defmacro my-when (condition &rest body)
  (list 'if condition (cons 'progn body)))

(macroexpand '(my-when t
         (message "hello world I did it")))
#+end_src