let

问题 In many functional programming languages, it is possible to "redefine" local variables using a let expression: let example = let a = 1 in let a = a+1 in a + 1 I couldn't find a built-in Prolog predicate for this purpose, so I tried to define a let expression in this way: :- initialization(main). :- set_prolog_flag(double_quotes, chars). replace(Subterm0, Subterm, Term0, Term) :- ( Term0 == Subterm0 -> Term = Subterm ; var(Term0) -> Term = Term0 ; Term0 =.. [F|Args0], maplist(replace(Subterm0

问题 In many functional programming languages, it is possible to "redefine" local variables using a let expression: let example = let a = 1 in let a = a+1 in a + 1 I couldn't find a built-in Prolog predicate for this purpose, so I tried to define a let expression in this way: :- initialization(main). :- set_prolog_flag(double_quotes, chars). replace(Subterm0, Subterm, Term0, Term) :- ( Term0 == Subterm0 -> Term = Subterm ; var(Term0) -> Term = Term0 ; Term0 =.. [F|Args0], maplist(replace(Subterm0

问题 In many functional programming languages, it is possible to "redefine" local variables using a let expression: let example = let a = 1 in let a = a+1 in a + 1 I couldn't find a built-in Prolog predicate for this purpose, so I tried to define a let expression in this way: :- initialization(main). :- set_prolog_flag(double_quotes, chars). replace(Subterm0, Subterm, Term0, Term) :- ( Term0 == Subterm0 -> Term = Subterm ; var(Term0) -> Term = Term0 ; Term0 =.. [F|Args0], maplist(replace(Subterm0

问题 In many functional programming languages, it is possible to "redefine" local variables using a let expression: let example = let a = 1 in let a = a+1 in a + 1 I couldn't find a built-in Prolog predicate for this purpose, so I tried to define a let expression in this way: :- initialization(main). :- set_prolog_flag(double_quotes, chars). replace(Subterm0, Subterm, Term0, Term) :- ( Term0 == Subterm0 -> Term = Subterm ; var(Term0) -> Term = Term0 ; Term0 =.. [F|Args0], maplist(replace(Subterm0

问题 In many functional programming languages, it is possible to "redefine" local variables using a let expression: let example = let a = 1 in let a = a+1 in a + 1 I couldn't find a built-in Prolog predicate for this purpose, so I tried to define a let expression in this way: :- initialization(main). :- set_prolog_flag(double_quotes, chars). replace(Subterm0, Subterm, Term0, Term) :- ( Term0 == Subterm0 -> Term = Subterm ; var(Term0) -> Term = Term0 ; Term0 =.. [F|Args0], maplist(replace(Subterm0

问题 I'm trying to understand why let is needed. In the example below I have a class Test with a function giveMeFive: public class Test() { fun giveMeFive(): Int { return 5 } } Given the following code: var test: Test? = Test() var x: Int? = test?.giveMeFive() test = null x = test?.giveMeFive() x = test?.let {it.giveMeFive()} x gets set to 5, then after test is set to null, calling either of the following statements return null for x. Given that calling a method on a null reference skips the call

问题 Is Kotlin ?.let thread-safe? Let's say a variable can be changed in different thread. Is using a?.let { /* */ } thread-safe? If it's equal to if (a != null) { block() } can it happen that in if it's not null and in block it's already null? 回答1: a?.let { block() } is indeed equivalent to if (a != null) block() . This also means that if a is a mutable variable, then: a might be reassigned after the null check and hold a null value when block() is executed; All concurrency-related effects are in

来源： https://stackoverflow.com/questions/49247362/safari-bug-with-block-scoped-variables

问题 When inspecting scopes of a function in the DevTools console I noticed a "script" scope. After a bit of research it seems to be created for let and const variables. Scopes of a function in a script without const or let variables: Scopes of a function in a script with a let variable: Yet the following prints 1 in the console - variables in the script scope can still be accessed from other scripts: <script>let v = 1</script> <script>console.log(v)</script> I've heard of ES6 modules in which top

问题 When inspecting scopes of a function in the DevTools console I noticed a "script" scope. After a bit of research it seems to be created for let and const variables. Scopes of a function in a script without const or let variables: Scopes of a function in a script with a let variable: Yet the following prints 1 in the console - variables in the script scope can still be accessed from other scripts: <script>let v = 1</script> <script>console.log(v)</script> I've heard of ES6 modules in which top