How to use a non-default table column separator in Asciidoc alvin December 9, 2019 - 12:04pm

As a brief note, if you ever need to use a different column separator when creating a table in Asciidoc, you can do so by specific the separator field in the table preamble.

For example, in the following Asciidoc table I can’t use the default pipe character | to separate the table columns, because I need to use that character in the content inside the table, so I set the separator character to be : instead:

<<methods_to_combine_cmds>> lists the ...

.Methods to combine external commands
:Methods :Description
:`cmd1 #| cmd2`  :The output of the first ...
:`cmd1 ### cmd2` :`cmd1` and `cmd2` will be ...
:`cmd1 #> cmd2`  :Normally used to write to ...
:`cmd1 #&& cmd2` :Run `cmd2` if `cmd1` runs ...
:`cmd1 #|| cmd2` :Run `cmd2` if `cmd1` ...
:`cmd1 #&& cmd2 #|| cmd3` :Run `cmd2` is ...

I shortened that content so you don’t have to read through all the non-essential text, but the image shows the actual resulting Asciidoc table.

For more information, this URL was the most helpful resource for me. This other page shows how you can specify format="csv" to create a table from a CSV-style syntax.

In summary, if you needed to see how to create an Asciidoc table with a non-default table column separator, I hope this example is helpful.

Dotty (Scala 3) v20 for/do loop syntax alvin November 26, 2019 - 12:35pm

Just fooling around a little bit at the moment, here are several ways to write for/do blocks with the “significant indentation” style in Dotty (Scala 3) as of Dotty v20:

Explaining Scala’s `val` function syntax

This is an excerpt from my book on Functional Programming in Scala. It’s an appendix that “explains and explores” Scala’s function syntax.


I wrote in the “Functions are Values” lesson that most developers prefer to use the def syntax to define methods — as opposed to writing functions using val — because they find the method syntax easier to read than the function syntax. When you write methods, you let the compiler convert them into functions with its built-in “Eta Expansion” capability. There’s nothing wrong with this. Speaking as someone who used Java for 15+ years, the def syntax was easier for me to read at first, and I still use it a lot.

Scala immutable Map class: methods, examples, and syntax

This page contains a large collection of examples of how to use the Scala Map class. There are currently well over 100 examples.

A Scala Map is a collection of unique keys and their associated values (i.e., a collection of key/value pairs), similar to a Java Map, Ruby Hash, or Python dictionary.

Scala match/case expressions (syntax, examples)

Table of Contents1 - Scala match expressions2 - Aside: A quick look at Scala methods3 - Using a match expression as the body of a method4 - Handling alternate cases5 - Using if expressions in case statements6 - Even more ...

This is a lesson on Scala match/case expressions from my book, Hello, Scala.

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Scala match expressions

Scala has a concept of a match expression. In the most simple case you can use a match expression like a Java switch statement:

// i is an integer
i match {
    case 1  => println("January")
    case 2  => println("February")
    case 3  => println("March")
    case 4  => println("April")
    case 5  => println("May")
    case 6  => println("June")
    case 7  => println("July")
    case 8  => println("August")
    case 9  => println("September")
    case 10 => println("October")
    case 11 => println("November")
    case 12 => println("December")
    // catch the default with a variable so you can print it
    case _  => println("Invalid month")

As shown, with a match expression you write a number of case statements that you use to match possible values. In this example I match the integer values 1 through 12. Any other value falls down to the _ case, which is the catch-all, default case.

TextMate TODO tag syntax highlighting

As a brief note to self, I like the way the TODO tag is highlighted when using TextMate, so I dug around to see how it worked so I can make other words be highlighted the same way it is. The short answer is that in TextMate, click the Bundles menu, select Edit Bundles, then scroll down to select TODO near the bottom of the list, then Language Grammars and TODO. The last few steps are shown in the image.

Kotlin collections methods: examples and syntax

As a quick note today, if you ever need some examples of how the Kotlin collections methods work, I hope these examples are helpful.

Sample data

First, here’s some sample data:

val a = listOf(10, 20, 30, 40, 10)
val names = listOf("joel", "ed", "chris", "maurice")

The Kotlin forEach println syntax

It’s a little hard to move back and forth between Scala and Kotlin because of some of the differences between the languages. Skipping the long story, here’s an example of how to print every line in a list of strings in Kotlin using forEach and println. First the setup:

fun readFile(filename: String): List<String> = File(filename).readLines()
val lines = readFile("/etc/passwd")

Then here are two different ways to use forEach with println: