Re:Show HN: Python library for functional programming
by lmm on Friday December 15, 2017 @06:58PM
(#15936365)
> The meaning of a program is its behavior, period. If reality doesn't agree with your views, it's your fault, not reality's.
That's not the usual meaning of, well, meaning.
> Standard ML doesn't give you any way to get the memory address of a particular value, so values that are semantically identical are actually indistinguishable in practice.
Just tried it to be sure:
fun address i = Unsafe.cast(ref i) : Int32.int ;;
val a = 4 :: nil ;;
val b = 4 :: nil ;;
address (a) ;;
address (b) ;;
address (a) ;;
val address = fn : 'a -> Int32.int
val a = [4] : int list
val b = [4] : int list
val it = ~175003712 : Int32.int
val it = ~174998232 : Int32.int
val it = ~175003712 : Int32.int
Re:Show HN: Python library for functional programming
by catnaroek on Saturday December 16, 2017 @04:39AM
(#15938698)
SML/NJ is not an implementation of Standard ML. It's known to be non-conformant in several ways: http://mlton.org/SMLNJDeviations
The meaning of a program is its behavior, period. If reality doesn't agree with your views, it's your fault, not reality's.
> Any practical programming language will give you some way to find the memory address of a particular value, so values that we usually consider as semantically identical are not actually indistinguishable in practice.
Standard ML doesn't give you any way to get the memory address of a particular value, so values that are semantically identical are actually indistinguishable in practice.
> We deal with this by only assigning semantics to a subset of the language that excludes those operations.
That doesn't make sense. Semantics is a property of the real programming language you are using, not the fictitious one you wish you were using.