* These built-in types: cons sym fn char string int num table output input socket exception thread

* Function calls

* First class lexically scoped functions, including closures (this one has a very complex implementation)

* Required function arguments, optional function arguments, rest function arguments, list destructuring

* Tail call elimination

* Macros (which are just functions annotated with a type of 'mac)

* First-class undelimited continuations (this one has a very complex implementation)

* These special forms: quote quasiquote if fn assign

* Special compiler optimizations for these functions: compose complement andf

* Ssyntax ~ : & (which expands to complement, compose, andf)

* Ssyntax . ! (which expands to function call, function call + quote)

* [ _ ] partial application

* Racket S-expression syntax () [] . ' ` , @ " ; #\ #| |#

* If enabled, you can use atstrings like "foo@bar" which is equivalent to (+ "foo" bar)

* These built-in functions: is < > + - * / mod expt sqrt apply cons car cdr err len annotate type rep uniq ccc infile outfile instring outstring inside stdout stdin stderr call-w/stdin call-w/stdout readc readb peekc writec writeb write disp sread coerce open-socket socket-accept setuid new-thread kill-thread break-thread current-thread sleep pipe-from table maptable protect rand dir file-exists dir-exists rmfile mvfile macex macex1 eval on-err details scar scdr sref bound newstring trunc exact msec current-process-milliseconds current-gc-milliseconds seconds client-ip atomic-invoke dead flushout ssyntax ssexpand quit close force-close memory declare timedate sin cos tan asin acos atan log

* These built-in variables: sig nil t

* Threads and atomics

* Sockets and file I/O

* Exception handling (err and on-error)