modules
	information hiding in modules - hide uncertain things that may change behind interfaces that need not - see On The Criteria to be Used in Decomposing Systems into Modules
structured programming
higher-order functions
lazy evaluation
multi-mode relations
graphs
generics
types
hooks
object-orientation / polymorphism

graphs
namespaces
macros
rewrite
relations
functions
procedures
lambda
concatenative
code as data
quote
monad
arrow
transparent monad
transparent reference
call / apply
lisp / scheme / racket
forth / joy
prolog / mercury
dataflow / FBP
explicit dispose
processes
python
algebraic types
lazy / futures / promise / on demand
blocking call = non-blocking call + register for signal + wait for signal
Use hashs / dictionaries, and other data structures.  Make them easy to use.
define a dictionary from existing variables using their names as keys, e.g. a = 1 ; b = 2 ; { a, b }  gives  { 'a': 1, 'b': 2 }
foo.bar is better than foo['bar']
efficient introspection by macros, lift the level so can wrap basic operations, e.g. wrap 'set' to trace changes to variables, wrap 'get' to trace variable usage, wrap 'call' to trace all function calls, wrap 'return' to trace return values
interning values (symbols, strings, structs...)
continuations ?