Foundations of Functional Programming

ions are compiled to the closure command, which will push a closure onto the Stack. The closure will include the current Environment and will hold M as a list of commands, from compilation: [[x:M ]] = closure(x; [[M ]]) Applications are compiled to the app command at compile time. Under the interpreted SECD machine, this work occurred at run time: [[MN ]] = [[N ]]; [[M ]]; app We could add further instructions, say for conditionals. Let test(C 1 ; C 2 ) be replaced by C 1 or C 2 , depending upon whether the value on top of the Stack is true or false : [[ if E then M else N ]] = [[E]]; test([[M ]]; [[N ]]) To allow built-in 2-place functions such as + and \Theta could be done in several ways. Those functions could be made to operate upon ordered pairs, constructed using a pair instruction. More efficient is to introduce arithmetic instructions such as add and mult , which pop both their operands from the Stack. Now ((x y:x + y) 3) 5 compiles to const(5); const(3); closure(x; C..