How to use multiple Futures in a Scala for-comprehension

If you want to create multiple Scala Futures and merge their results together to get a result in a for comprehension, the correct approach is to (a) first create the futures, (b) merge their results in a for comprehension, then (c) extract the result using onComplete or a similar technique.

How to merge (concatenate) Lists in Scala

This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 11.5, “How to Merge (Concatenate) Lists in Scala”


You want to merge/concatenate the contents of two lists.


Merge two lists using the ++, concat, or ::: methods. Given these two lists:

Scala: How to merge two sequential collections into pairs with ‘zip’

This is an excerpt from the Scala Cookbook, partially modified for the internet. This is Recipe 10.23, “How to Merge Two Sequential Collections into Pairs with the zip method”


You want to merge data from two sequential collections into a collection of key/value pairs.


Use the zip method that’s available to Scala sequential collections to join two sequences into one:

How to merge Scala sequential collections (List, Vector, ArrayBuffer, Array, Seq)

This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 10.22, “How to Merge Scala Sequential Collections”


You want to join two sequences into one sequence, either keeping all of the original elements, finding the elements that are common to both collections, or finding the difference between the two sequences.


There are a variety of solutions to this problem, depending on your needs:

Scala List class examples: range, fill, tabulate, appending, foreach, more ...

Scala List FAQ: Can you share some Scala List class examples?

The Scala List class may be the most commonly used data structure in Scala applications. Therefore, it's very helpful to know how create lists, merge lists, select items from lists, operate on each element in a list, and so on.

In this tutorial, I'll try to share examples of the most common List operations (methods).

Scala - Merging two Arrays or ArrayBuffers

Scala Array FAQ: How do I merge two Arrays or ArrayBuffers?

Solution: Use the ++ method to join two arrays into one new array:

scala> val a = Array(1,2,3)
a: Array[Int] = Array(1, 2, 3)

scala> val b = Array(4,5,6)
b: Array[Int] = Array(4, 5, 6)

scala> val c = a ++ b
c: Array[Int] = Array(1, 2, 3, 4, 5, 6)


Use the same approach to merge two ArrayBuffers into a new ArrayBuffer:

The Git 'topic branch' workflow (pattern)

In this short article, I'll demonstrate the typical workflow for using a Git topic branch. If you've never heard of a topic branch, here's a description from the excellent book, Pro Git:

"A topic branch is a short-lived branch that you create and use for a single particular feature or related work.

How to merge Scala Lists

Scala List FAQ: How do I merge a List in Scala?

NOTE: I wrote the solutions shown below a long time ago, and they are not optimal. I'll update this article when I have more time. The best approach is to prepend one List to the beginning of another List with the :: method.

There are at least three ways to merge/concatenate Scala List instances, as shown in the examples below.

How to concatenate strings in Perl

A Perl FAQ is "How do you concatenate (merge) two or more strings in Perl?"

Use the "." operator

The short answer is that you use the . operator. Here's a simple example:

$name = "alvin" . " " . "alexander";

Of course I could have also done that like this:

$name = "alvin " . "alexander";

but I wanted to show an example with more than two strings.

AppleScript string tip: How to concatenate strings

AppleScript string FAQ: How do I concatenate (merge) strings in AppleScript?

Fortunately string concatenation in AppleScript is pretty easy (if not a little different). To concatenate strings in AppleScript just use the ampersand (&) operator.

Here are a few AppleScript string concatenation examples, with a dialog thrown in so you can see the result: