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comparison 4-Scala/README.txt @ 70:4198fa4e0df4
Add Scala code and notes
| author | IBBoard <dev@ibboard.co.uk> |
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| date | Sat, 14 Oct 2017 13:39:41 +0100 |
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| 69:05871e7ac124 | 70:4198fa4e0df4 |
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| 1 I've already done Scala development at work, so most of this is just a recap. | |
| 2 | |
| 3 A few things I learned: | |
| 4 | |
| 5 * Never used traits before - mini classes defined with "trait" keyword and included | |
| 6 like a "mixin" with the "with" keyword to 'inherit' functionality from multiple parents | |
| 7 * Nil is an empty list - probably useful when iterating things and returning a Nil | |
| 8 * foldLeft either uses strange syntax ("start /: list {(a, b) … }") or uses currying | |
| 9 ("list.foldLeft(start)((a,b) …)") | |
| 10 * Strings can be converted to regexes by adding ".r" at the end (I think my work code | |
| 11 managed to do without string matching) | |
| 12 * Pattern matching with a "match… case" on XML can use squiggly brackets to name a variable | |
| 13 (e.g. "case <movie>{movieName}</movie>" matches the tag and puts the contents in movieName) | |
| 14 * Scala has a few minor problems: | |
| 15 * 2.12 (RPM from the website) won't run files as "scala filename.scala" - it needs to be | |
| 16 "scala -nc filename.scala" to disable the compilation daemon | |
| 17 * "scala -e <code>" doesn't seem to want to work without "-nc" either | |
| 18 * If there are dependencies then it is easier to use sbt. Download from | |
| 19 http://www.scala-sbt.org/download.html, create a standard "project/src/scala/package" | |
| 20 structure then create build.sbt within "project/" with the contents: | |
| 21 name := "Project-Name" | |
| 22 version := "1.0" | |
| 23 scalaVersion := "2.12.3" | |
| 24 Run the project by cd-ing into the project directory and running "sbt run" | |
| 25 * Actors have been deprecated and replaced by Akka | |
| 26 * sbt compiles code, so you can't have code outside a class or object | |
| 27 * Akka actors can only act - they can't easily have other methods as well because | |
| 28 creation returns a generic Akka reference to the actor, which doesn't expose the method |