Why

I find the tour of scala a nice idea, but very difficult to follow for a few reasons:

• The level of the tour elements skips from extremely basic to beyond advanced without a good guide through. This has left me scratching my head at some of the more advanced concepts.
• Many of the features are demonstrated via mathematical conecpts or completely arbitrary calculations (how often do I need to take a list and arbitrarily modulo its contents into a new list?)
• Some features are demonstrated by setting up a convoluted problem that the feature magically solves, leaving me wondering why the feature even exists, when a simpler design for the problem at hand would have obviated the need for it.
• The more advanced topics are described in very terse format and difficult to understand without what I assume is a deep understanding of Scala already or some other functional programming language.

So, I’m going through each thing and trying to:

• Order them sensibly, so previous topics support future ones
• Create more real-world situations where a feature might be useful (I make you this promise: The word “monoid” will never be used again in these pages)
• Comment on my own thoughts as to the utility of the feature.

I’m also a Java programmer by trade, so a lot of the “justification” aspects that come to me are in comparison to Java.

The Tour

Basics

• UnifiedTypes
• ScalaBasics(Basics)
• ScalaClasses(Classes)
• ScalaTraits(Traits)
• ScalaGenerics(Generics)
• ScalaAnnotations(Annotations)

Intermediate

• Some ScalaFunctions and stuff
• PatternMatching
• FunctionCurrying – define a function that has received some of its parameters now, and will get the remainder later.
• CaseClasses – taking switch statements to a useful level.
• XmlLiterals
• ForComprehensions – don’t let the name confuse you; this is about Scala’s powerful for loop construct
• TypeBounds
• InnerClasses – you only thought they were basic.
• ImplicitConversions

Advanced

• TypeVariance
• AbstractTypes – not abstract classes
• ExplcitlyTypedSelfReferences

TODO

I haven’t looked at this and they are not all covered by the above (though some may be)

• TypeDependentClosures
• SealedClasses
• ScalaPackages
• ScalaOperators
• PredefinedFunctionClassOf
• LocalTypeInference
• ImplicitParameters
• HigherOrderFunctions
• ExtractorObjects