scala - Declaring functions two ways. What is the distinction? -

-

are these 2 function declarations different?

if not, why have different tostring values?

scala> def f: (int) => int = x=> x*x f: (int) => int  scala> def f(x: int) = x*x f: (int)int

the first no-argument method f1 returns function1[int, int].

scala> def f1: (int => int) = (x: int) => x * x f1: (int) => int

the second 1 argument method f2 takes an int , returns int.

scala> def f2(x: int): int = x * x f2: (x: int)int

you can invoke f1 , f2 same syntax, although when call f1(2) expanded f1.apply(2).

scala> f1 res0: (int) => int = <function1>  scala> f1(2) res1: int = 4  scala> f1.apply(2) res2: int = 2  scala> f2(2) res3: int = 4

finally, can 'lift' method f2 function follows.

scala> f2 <console>:6: error: missing arguments method f2 in object $iw; follow method `_' if want treat partially applied funct ion        f2        ^  scala> f2 _ res7: (int) => int = <function1>  scala> (f2 _).apply(2) res8: int = 4

exercise: type of f1 _?


Comments

Post a Comment

Popular posts from this blog

javascript - Enclosure Memory Copies -

-
function myclass() { //lots , lots of vars , code here. this.bar = function() { //do numerous enclosed myclass vars } this.foo = function() { alert('hello'); //don't enclosed variables. } } each instance of myclass gets own copy of bar , foo, why prototyped methods use less memory. however, know more memory use of inner methods. it seems obvious me (1) below must true. agree? not distinct myclass instances have own distinct copies of bar, must have own distinct copies of myclass enclosure. (or else how bar method keep myclass variables straight on per instance basis?) now (2) question i'm after. since inner foo method doesn't use in myclass enclosure natural qustion is: javascript smart enough not keep myclass enclosure in memory use of foo? this depend entirely on implementation not language. naive implementations keep far more around others. answer true e.g. v8 (chrome's js engine) may not true spider...
Read more

php - Replacing tags in braces, even nested tags, with regex -

-
example preg_replace('/\{[a-za-z.,\(\)0-9]+\}/', 'replaced', 'lorem ipsum dolor sit {tag1({tag2()})}, consectetur adipiscing elit.'); the result: lorem ipsum dolor sit {tag1(replaced)}, consectetur adipiscing elit. question as can see "tag2" has been replaced, want replace "tag1" know how can this? (in cases might this: {tag1({tag2({tag3()})})}) , on.) btw using preg_replace_callback, easier show preg_replace here site can test code: http://www.spaweditor.com/scripts/regex/index.php you need add curly braces character set. here's pattern used: /\{[a-za-z.,\(\)\{\}0-9]+\}/ and here result: "lorem ipsum dolor sit replaced, consectetur adipiscing elit."
Read more