Posts Tagged ‘ScalaProgramming’
[DevoxxBE2012] First Steps with Scala (Part 1/2)
In an engaging session, Dick Wall and Bill Venners, co-founders of Escalate Software and prominent figures in the Scala community, introduced newcomers to the Scala programming language. Dick, known for his JavaPosse involvement, and Bill, president of Artima and author of key Java texts, adapted their training curriculum to cover foundational elements. Their approach fused object-oriented and functional paradigms, emphasizing Scala’s blend of familiarity and innovation.
They commenced with the Scala REPL, a tool they use daily for experimentation. This interactive shell allows immediate code execution, inferring types and storing results for reuse, making it invaluable even for Java developers exploring libraries.
Dick and Holly—wait, Dick and Bill—highlighted Scala’s strong typing with inference, reducing boilerplate while maintaining safety. They demonstrated basic operations, showing how everything integrates into a unified hierarchy, unlike Java’s primitives and references.
Defining Variables and Immutability
Transitioning to variables, Dick and Bill distinguished between vals (immutable) and vars (mutable), promoting vals for reliability. This design choice encourages constant use without extra syntax, contrasting Java’s final keyword. They illustrated reassignment errors, noting REPL’s scoping allows redefinitions, mimicking nested blocks.
Type specifications, optional due to inference, follow names with colons, inverting Java’s order for natural flow. Examples showed string inferences and explicit declarations, underscoring flexibility.
They addressed mutability choices, advising private volatile vars for necessary changes, or mutable objects within immutable structures, depending on context.
Control Structures and Expressions
Dick and Bill explored control structures, revealing Scala’s expression-oriented nature. If statements return values, enabling concise assignments without ternaries. While loops, though imperative, yield Unit, encouraging functional alternatives.
For comprehensions, powerful for iteration, support guards and yields, transforming collections declaratively. They demonstrated filtering even numbers or yielding transformed lists, highlighting pattern matching integration.
Try-catch blocks, also expressions, handle exceptions functionally, with finally clauses for cleanup. This uniformity simplifies code, treating controls as value producers.
Functions and Closures
Delving into functions, they defined them as objects, enabling higher-order usage. Simple defs showed parameter typing and inference, with return types often omitted.
Function literals, akin to lambdas, capture environments as closures, allowing deferred execution. Examples illustrated anonymous functions for mapping or filtering, emphasizing Scala’s functional leanings.
They introduced by-name parameters for lazy evaluation, useful in custom controls like loops, mimicking built-in syntax without special privileges.
Collections and Functional Programming
Scala collections, immutable by default, support transformations via methods like map and filter. Dick and Bill showcased creating lists, accessing elements, and applying operations, yielding new collections without mutation.
They contrasted mutable variants, advising caution for concurrency. For comprehensions over collections generate new ones, combining iteration with functional purity.
Approaching functional style, they encouraged avoiding side effects, using recursion or folds for aggregations, fostering predictable code.
Advanced Basics and Q&A Insights
In Q&A, they addressed optimizations: Scala uses primitives internally, with @specialized for generics avoiding boxing. Profiling mirrors Java tools, with quirks in coverage.
Dick and Bill wrapped by previewing afternoon labs on Scala Koans, urging practice. Their session laid a solid groundwork, blending theory with practical demos, preparing attendees for Scala’s expressive power.