Frequently-used Lisp functions are exposed as methods on env:

# #![allow(unused_variables)]
#fn main() {
env.intern("defun")?;

env.message("Hello")?;

env.type_of(5.into_lisp(env)?)?;

env.provide("my-module")?;
#}

To call arbitrary Lisp functions, use env.call(&str, &[Value]):

# #![allow(unused_variables)]
#fn main() {
// (list "1" 2)
env.call("list", &[
    "1".into_lisp(env)?,
    2.into_lisp(env)?,
])?;

// (add-hook 'text-mode-hook 'variable-pitch-mode)
env.call("add-hook", &[
    env.intern("text-mode-hook")?,
    env.intern("variable-pitch-mode")?,
])?;
#}