Scala skill levels

scalaskilset.markdown

Proposed levels of skill for the scala programming language, can be used as a base for a curriculum

Related links:

• the scala style guide.
• a scala basic exam
• examples of scala abuses
• sample training curriculum Artima

Level A1: Beginning application programmer

• Java-like statements and expressions: standard operators, method calls, conditionals, loops, try/catch
• class, object, def, val, var, import, package
• Infix notation for method calls
• Simple closures
• Collections with map, filter, etc
• for-expressions

Level A2: Intermediate application programmer

• Pattern matching
• Trait composition
• Recursion, in particular tail recursion
• XML literals

Level A3: Expert application programmer

• Folds
• Streams
• Actors
• Combinator parsers

Level L1: Junior library designer

• Type parameters
• Traits
• Lazy vals
• Control abstraction, currying
• By-name parameters

Level L2: Senior library designer

• Variance annotations
• Existential types (to interface with Java wildcards)
• Abstract types
• Self types
• Structural types
• Extractors

Level L3: Expert library designer

• Early initializers
• Implicit definitions
• Higher-kinded types
• Defining map/flatmap/withFilter for new kinds of for-expressions