TODO: Document more...
string?, symbol?, number?, pair?, closure?, macro?, procedure? and boolean? return true for their appropriate types or false otherwise.
display writes a single object to the console (it may be abbreviated if it's a complex object)
strlen returns the length of a string.
strcat accepts two strings and returns a string containing the contents of the first string followed by the contents of the second string.
+, -, * and / correspond to their equivalent mathematical functions.
save-state and resume-state save and restore program state to a file (named by the first argument).
Upon saving program state, the symbol saved is returned upon success. If the saved state is later restored, the call to resume-state will effectively replace the running program with the program in the given state file, and will be as though the original call to save-state returns the symbol restored to it's caller.
(Unix programmers may find the persistence functions comparable to fork and exec calls, except that forked processes are saved to disk instead of being immediately invoked.)
TODO: Document more...