loop

Kotlin FAQ: How do I iterate over a Map in Kotlin?

Solution: Here’s an example of how to iterate over a Kotlin Map using a for loop:

val map = mapOf("a" to 1, "b" to 2, "c" to 3)

for ((k,v) in map) {
    println("value of $k is $v")
}

I just found some notes from when I first began working with Scala, and I was working with the yield keyword in for loops. If you haven't worked with something like yield before, it will be helpful to know how it works. Here's a statement of how the yield keyword works in for loops, based on the documentation in the book, Programming in Scala:

If you need to iterate over the elements in a Map in Java 8, this source code shows how to do it:

Map<String, String> map = new HashMap<String, String>();
map.put("first_name", "Alvin");
map.put("last_name",  "Alexander");

// java 8
map.forEach((k,v)->System.out.println("key: " + k + ", value: " + v));

Scala FAQ: How can I iterate through each character in a Scala String, performing an operation on each character as I traverse the string?

Solution

Depending on your needs and preferences, you can use the Scala map or foreach methods, a for loop, or other approaches.

The map method

Here’s a simple example of how to create an uppercase string from an input string, using the map method that’s available on all Scala sequential collections:

Here's a quick look at how to use the Scala Map class, with a colllection of Map class examples.

The immutable Map class is in scope by default, so you can create an immutable map without an import, like this:

val states = Map("AL" -> "Alabama", "AK" -> "Alaska")

To create a mutable Map, import it first:

Scala Map FAQ: How can I iterate/loop over a Scala Map?

There are several different ways to iterate over a Scala Map, and the method you choose depends on the problem you need to solve.

To get started with our examples, let's create a simple Map we can work with:

Shortly after writing my Arduino Uno Hello, World example, I read my documentation a little more, learned that Pin 9 on the Arduino Uno board is an analog pin, switched the LED wire to that pin, and created the following program, which slowly lights up the LED using an analog programming approach, and then fades the LED light out.

Here's the source code for my LED fade sketch:

AppleScript for loop FAQ: How do I use an AppleScript for loop? (Also, how do you use an AppleScript while loop?)

This is actually a bit of a trick question, as there is no AppleScript for loop or while loop syntax. Instead you use the AppleScript repeat command, as shown in the following examples.

AppleScript for loop examples

Where you might expect an AppleScript for loop to iterate over a list, you use the AppleScript repeat with syntax: