DONE: rework type system
DONE: var decl with a type, but no value
DONE: type casting
DONE: remove optimization option
DONE: conditionals
DONE: if-then-else
DONE: chained if-then-else
DONE: optional block around a path if it's only one statement
DONE: while-then
DONE: for-then
DONE: break and continue statements
DONE: truthiness rethink
DONE: string concat with the + operator
DONE: increment & decrement operators
DONE: store compound types in variables
DONE: +=  -=  *=  /=  %= operators
DONE: && and || operators
DONE: functions are invoked by calling their names
DONE: function arguments can have specified types
DONE: function returns can have specified types
DONE: closures are explicitly supported


TODO: functions take a set number of parameters
TODO: functions can return a set number of values
TODO: functions are first-class citizens
TODO: functions last argument can be a rest parameter
TODO: check for wrong number of function parameters

TODO: Nullish types
TODO: A way to check the type of a variable (typeOf keyword)
TODO: a = b = c = 1; ?
TODO: are compounds shallow or deep copies?
TODO: Assertion-based test scripts
TODO: standard library
TODO: external runner library