Coding idioms, or patterns, often take up a significant part of a project's codebase. One such idiom is the Java try-catch-finally pattern used to ensure that access to some resource is properly relinquished, even if using the resource results in exceptions.

Another, more general, coding pattern that developers sometimes follow calls for wrapping an already existing library, possibly extending that library with new functionality without having to have access to, and recompile, the library source code.

Some languages afford more concise implementations of these, and other, coding patterns. Scala developers, for example, identified two Scala patterns that implement the above mentioned idioms. Luis Diego Fallas describes in Improving code using more Scala features how these patterns can result in shorter and, at the same time, easier-to-understand code.

The Loan pattern is a way to ensure resource disposal when the control leaves some scope. For this purpose closures are used.

The Pimp my library pattern, based on a Martin Odersky’s article, provides a way to extend existing class libraries with new operations without recompiling. New operations are added by defining a wrapper for specific classes.

Interestingly, Fellas illustrates these patterns in the course of implementing in Scala a code-hint for the NetBeans editor, for use when editing Ruby code with the IDE. Fellas' blog post also shows how such editor hints can be coded up in Scala with relatively few lines of code, and how Scala's compatibility with the Java runtime ensures that the resulting bytecodes run inside NetBeans.

What Scala coding idioms do you like the most? In general, what do you think about Scala's impact on programmer productivity?