threading macro -> with anonymous functions
You can have anonymous functions in Clojure macros. You are having problems, because you are missing some parentheses. 🙂 Your example is edited below. (-> 4 (#(+ % 1)) (#(- % 1)) (#(+ % 1)))
lambda
Interview: What is Lambda expression? [closed]
Lambda Expressions are nameless functions given as constant values. They can appear anywhere that any other constant may, but are typically written as a parameter to some other function. The canonical example is that you’ll pass a comparison function to a generic “sort” routine, and instead of going to the trouble of defining a whole … Read more
Reference to method of a particular instance in Kotlin
Since Kotlin 1.1, you can use bound callable references to do that: val f = a::getItem list.forEach(myObject::myMethod) Earlier Kotlin versions don’t have this feature and require you to make a lambda every time except for these simple cases.
Lazy field initialization with lambdas
Within your actual lambda, you can simply update the fooField with a new lambda, such as: class A<T>{ private Supplier<T> fooField = () -> { T val = expensiveInit(); fooField = () -> val; return val; }; public T getFoo(){ return fooField.get(); } } Again this solution is not thread-safe as is the .Net Lazy<T>, … Read more
How did lambda expressions get their name? [closed]
The term derived from mathematical key word only. Wiki info : Lambda calculus check this : http://dictionary.reference.com/browse/lambda+expression
Consumer with more than one argument in Java 8?
For 3 and more arguments you could use curried(http://en.wikipedia.org/wiki/Currying) functions with last consumer: Function<Double, Function<Integer, Consumer<String>>> f = d -> i -> s -> { System.out.println(“” + d+ “;” + i+ “;” + s); }; f.apply(1.0).apply(2).accept(“s”); Output is: 1.0;2;s It’s enough to have a function of one argument to express function of any number of … Read more
What is call/cc?
To compare it to C, the current continuation is like the current state of the stack. It has all the functions waiting for the result of the current function to finish so they can resume execution. The variable captured as the current continuation is used like a function, except that it takes the provided value … Read more
Java 8 lambda comparator with null value check [duplicate]
There are default implementations within Comparator you can use: nullsFirst or nullsLast: Comparator.comparing(YourObject::getStartDate, Comparator.nullsFirst(Comparator.naturalOrder()) )
Using return inside a lambda?
Just use the qualified return syntax: return@fetchUpcomingTrips. In Kotlin, return inside a lambda means return from the innermost nesting fun (ignoring lambdas), and it is not allowed in lambdas that are not inlined. The return@label syntax is used to specify the scope to return from. You can use the name of the function the lambda … Read more
Passing lambda instead of interface
As @zsmb13 said, SAM conversions are only supported for Java interfaces. You could create an extension function to make it work though: // Assuming the type of dataManager is DataManager. fun DataManager.createAndSubmitSendIt(title: String, message: String, progressListener: (Long) -> Unit) { createAndSubmitSendIt(title, message, object : ProgressListener { override fun transferred(bytesUploaded: Long) { progressListener(bytesUploaded) } }) } … Read more