Questions tagged [function-literal]
38 questions
46
votes
3 answers
The argument types of an anonymous function must be fully known. (SLS 8.5)
I have a function literal
{case QualifiedType(preds, ty) =>
t.ty = ty ;
Some((emptyEqualityConstraintSet,preds)) }
Which results in an error message
missing parameter type for expanded function The argument types of an…
Theodore Norvell
- 15,366
- 6
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- 45
19
votes
2 answers
Multiline function literal as arguments in Scala
I always wondered why sometimes with function literals we can ignore the curly brace even for multiple statements. To illustrate this, the syntax for a multiline function literal is to enclose the statements with curly braces. Like so,
val fl = (x:…
altcoder
- 340
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16
votes
16 answers
Which languages support *recursive* function literals / anonymous functions?
It seems quite a few mainstream languages support function literals these days. They are also called anonymous functions, but I don't care if they have a name. The important thing is that a function literal is an expression which yields a function…
Hugh Allen
- 6,509
- 1
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14
votes
6 answers
Exact meaning of Function literal in JavaScript
In JavaScript there are both Object literals and function literals.
Object literal:
myObject = {myprop:"myValue"}
Function literal:
myFunction = function() {
alert("hello world");
}
What is the significance of the word literal? Can we say Java…
dublintech
- 16,815
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8
votes
3 answers
JavaScript Object literal method: Recursive call
Is it possible to call recursively a method from an object literal?
For example:
(function () {
'use strict';
var abc = ['A', 'B', 'C'],
obj = {
f: function () {
if (abc.length) {
…
user972959
- 381
- 3
- 5
7
votes
1 answer
How should I avoid unintentionally capturing the local scope in function literals?
I'll ask this with a Scala example, but it may well be that this affects other languages which allow hybrid imperative and functional styles.
Here's a short example (UPDATED, see below):
def method: Iterator[Int] {
// construct some large…
Scott Morrison
- 3,100
- 24
- 39
5
votes
1 answer
Scala underscore use to simplify syntax of function literals
I have the following code:
var x = Array(1,3,4,4,1,1,3)
var m = Int.MaxValue
x.foreach((x)=>(m = m min x))
I tried to simplify last sentence to:
x.foreach((m = _ min m))
But the interpreter says:
scala> x.foreach((m = _ min m))
:8:…
Stan
- 73
- 1
- 4
5
votes
5 answers
how to simplify scala's function literal like this?
I'm new to scala and trying to write a function literal that check whether a given integer is odd or not.
my first attempt is:
val isOdd = (x:Int) => (x & 1) == 1
it works great, and, since the parameter x only appears once within this function…
hind_d
- 355
- 2
- 6
4
votes
2 answers
Scala Currying and function literals
I was reading the-neophytes-guide-to-scala-part-10 where I came across following code.
type EmailFilter = Email => Boolean
val minimumSize: Int => EmailFilter = n => email => email.text.size >= n
I understood the first line where type alias…
Kumar Waghmode
- 509
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- 18
4
votes
2 answers
Named functions in Javascript accessible before declaration, but function literals aren't
I'm trying to figure out how this works. When I reference a named Javascript function that hasn't been declared yet, in some circumstances, it works. But if I use a function literal, it doesn't, but it also doesn't fail with a…
David Ehrmann
- 7,366
- 2
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3
votes
2 answers
Questions about placeholders in Scala
Consider the following definition in Scala:
val f = ((_: Int) + 1).toString()
The code assigns to f the string representation of the function literal _ + 1, which is quite natural, except that this is not i want. i intended to define a function…
weidi
- 852
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3
votes
2 answers
How to define a function that takes a function literal (with an implicit parameter) as an argument?
I want to be able to do something on these lines (won't compile):
def logScope(logger:Logger)(operation: (implicit l:Logger) => Unit) {/* code */ operation(logger) /* code */}
def operationOne(implicit logger:Logger) {/**/}
def…
LastContrarian
- 33
- 4
3
votes
1 answer
Function Literal referencing by val and def
I'm trying to understand the crucial difference between these two approaches of referencing / defining Function Literal (reference to anonymous function):
By val
scala> val v2 = new Function[Int, Int] {
| def apply(a: Int): Int = a + 1
|…
ses
- 13,174
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2
votes
0 answers
How To Obtain An Annotation Of A Function Literal At Runtime
package _z_additional
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.TestInstance
import kotlin.reflect.KFunction
import kotlin.reflect.full.declaredMemberFunctions
import…
user5132301
2
votes
1 answer
What is the scala notation written as _:type?
I'm following the scala tutorial.
In function literal, it has a following notation:
(_ : *type*) => println("pressed")
For example,
(_ : Int) => println("pressed")
In this notation, I couldn't understand what (_ : type) means.
user7159879
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