Erik Meijer: The World According to LINQ (opens in new tab)

Unix shell scripts are fantastic for what they do. But most people find that it's easier (and more performant) to build, say, web applications using a programming language than by using shell scripts over CGI. Assuming you commit to a programming language, then you either then commit to multiparadigmatic programming and call out into shell whenever you need to do work like that, or you give up shell inside your program in favor of using the API tools inside the language. Outside of possibly perl, calling out into shell for things like that isn't very common anywhere I've ever worked, and with good reason.

Once you commit to a programming language instead of shell, then you have various types of IO to worry about. What you want might be in an array or list, a file, a database table, an xml file, or the response from a web service. Typically, you either need to write a decent chunk of code for each of these sources, either for abstraction or for marshaling.

With LINQ, all you need is a change in the upfront handling, and you can reuse the same comprehension logic across all the different data sources. This is a pretty nice deal, all things considered.

And really, one way of looking at adding comprehensions like this to languages is to make programming in languages more like chaining together code in a shell script -- something that programming in traditional Algol-descended languages is not normally like at all.

You're either trolling, or you've completely missed the point.

This is not an article about trivial word counting. This an article about mathematical abstractions behind all batch data processing (unix pipes included).

Just because we already know how to count small numbers of words in bash doesn't mean we can't learn anything from this article.

My apologies for being pedantic, but that's not quite right, to do something similar you'd need

  sed 's/ \+/\n/' words.txt | tr A-Z a-z | sort | uniq -c 

And to get the top five, you'd need another sort:

  sed 's/ \+/\n/' words.txt | tr A-Z a-z | sort | uniq -c | sort -gr | head -5

Where the delimiters of interest go where the space is in the sed expression. Of course, I can never remember what strange regex syntax sed uses, so I have spend 5 minutes trying to puzzle through man page.

Thats not exactly apples to apples. The powershell equivalent is probably more comparable.

Also, it all depends on what you value; cryptic one liners definitely will get you geek cred, but working with other people not as smart as you will not be fun when having to explain and maintain code like that.

Of course, you may never have to worry about that.

You may not realize it, but your little funny quip does actually rely on a deep mathematical equivalence: LINQ is basically syntax for monads, and unix shell programming can be seen as monadic, too: http://okmij.org/ftp/Computation/monadic-shell.html

So, in a way, yes, it is the same, but that is exactly the point.

Now use the same sytax to query yahoo weather. Get the point?

Put your cursor on the part of the expression that you want to debug and press F9 to set a breakpoint. Setting breakpoints by clicking in the gutter doesn't work for LINQ like you might expect - you have to use the hotkey.

I frequently hear complaints about debugging LINQ, but Visual Studio supports it well enough. Microsoft could have done a better job informing people about it.

I don't believe the VM is aware of LINQ at all. As far as optimization, there's no guarantee to pureness with CLR code, so the compiler/JIT cannot do very much. (That is, a query composed of multiple parts cannot be turned into a nice simple loop.) The generated code creates enumerable objects, and possibly closure objects which are called via delegates.

On the topic of multiplatform, Mono has been working very well for many people. http://www.mono-project.com/