conversion

How to convert a Java array into a Stream

If you ever need to convert a Java array into a Stream, there are at least two ways to do it.

1) Converting an array to a Stream

First, to convert the entire array to a Stream, use the Stream.of static method like this:

How to convert Docbook to AsciiDoc

If you ever need to convert Docbook to AsciiDoc, this Pandoc command seems to work well:

pandoc --wrap=none -f docbook -t asciidoc \
       DocbookFile.xml > AsciiDocFile.adoc

Scala number, date, and formatting examples

This short blog post contains a collection of Scala number and date examples. I created most of these in the process of writing the Scala Cookbook. Unlike the Cookbook, I don’t describe the examples here much at all, I just show the examples, mostly as a reference for myself (and anyone else that can benefit from them).

Scala numeric types

Scala has these numeric types:

Scala “string to date” and “date to string” methods

Here are a couple of “string to date” and “date to string” methods. They’re written in Scala, but are easily converted to Java. They only use the Java Date and SimpleDateFormat classes:

Getting started converting documents with Pandoc

I’m looking into producing my Scala/FP book as a PDF, and as part of that I have been looking into Pandoc. With the exception of converting HTML tables into other formats such as Markdown or LaTeX, Pandoc has been working well so far.

Here are a couple of Pandoc commands to show you how easy this is:

Safe String to Int conversion in Haskell (a string from the command line)

I was working on a Haskell factorial function (which turned out to be easy) and decided I wanted to write a program to prompt a user at the command line for an Int, and then do the factorial of that Int.

I quickly learned that this required a String to Int conversion, which I wanted to do safely (I didn’t want my program to blow up). Technically what I do is actually a String to Maybe Int conversion, as you can see in this code:

How to go to and from Java collections in Scala

This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 17.1, “How to go to and from Java collections in Scala.”

Problem

You’re using Java classes in a Scala application, and those classes either return Java collections, or require Java collections in their method calls.

Solution

Use the methods of Scala’s JavaConversions object to make the conversions work.

How to convert between numeric types in Scala

Scala FAQ: How do I convert between numeric types in Scala, such as from Int to Long, Int to Double, etc.?

Solution

Instead of using the “cast” approach in Java, use the to* methods that are available on all of Scala’s numeric types. These methods can be demonstrated in the REPL (note that you need to hit the [Tab] key at the end of the first example):