Ruby’s symbols are often talked about in terms of efficiency – taking up less memory and executing faster. While these are both laudable goals, symbols are more than just performance improvers. The ability to name things is valuable semantically. Take a look thru p&p’s Composite UI AppBlock and you’ll see strings used as names for things all over the place. It’s great for loose coupling, you see. But how do you tell the difference between a string used as a name and a string used for some other reason like user input? You can’t.

Rails makes extensive use of symbols – anyone who has Rolled on Rails has seen “scaffold :recipe”. That’s just the tip of the iceberg. Rails uses symbols extensively across both ActionPack and ActiveRecord (and probably others I’m not familiar with). It’s a great approach, but one that’s unique to Ruby as far as I’m aware.

Several languages, such as Python, have the concept of a Tuple built into the lanugage. One of things it’s used for in Python is multiple return values. So you can call “return x,y” to return two values. Of course, C# can only return one. If you need to return more values, you have to define out parameters.

LINQ / C# 3.0 / VB 9 support the idea of anonymous types, which is similar to a tuple. The big difference is that, because they’re anonymous, they can’t leave the scope they’re defined in. In other words, they’re great within a function, but if you want to pass them out of your function type-safely, you have to define a non-anonymous type for them.

Interestingly enough, F# supports tuples, though it a bit of a hack. Since the CLR doesn’t support tuples, F# basically defines different Tuple classes for up to seven tuple parameters (i.e. Tuple<t1,t2,t3,t4,t5,t6,t7>), For .NET 1.x, it’s even worse – they have to define different type names (Tuple2, Tuple3, etc). Ugh.

Update: Robert Pickering pointed out that F#’s tuple implementation is entirely transparent inside of F#. He’s right – I was writing from the perspective of a C# developer using F#’s implementation of tuples. Maybe I need to be looking closer at F#?