How do the languages compare when downloading a Web page?

First look

The first look on the downloading a web page tutorial explains the F# code as I have uploaded here. My first impressions are that it looks simple and comparable to C# but instead of the using keyword there is just use. I would expect this to behave in the same way. After reading the explanation of the code this is the case.

Testing interactively

I ran the example and was quite impressed. After studying the code I like the callback feature and can see how this would improve code reuse and writing generic functions. We now have a “fetchUrl” method that can be used in many different ways, we just happened to choose to print out the first 1000 characters of the response to google.

Baking in parameters

Being able to create a second fetch function that always uses the “myCallback” function is very impressive. My brain is always trying to compare this to what I know, which is C#, so in the last line of the baking in parameters example we have;

// test with a list of sites
let sites = ["http://www.bing.com";
             "http://www.google.com";
             "http://www.yahoo.com"]

// process each site in the list
sites |> List.map fetchUrl2

Which I know I could implement with link within a method call easily but with F# it just seems cleaner. I also know that I could bake in parameters by setting a default within a method in C# or creating a new method that just calls the method with a hardcoded value but again these solutions don’t seem as clean as the F# equivalent.

Reading the C# implementation that uses callbacks after reading into F# has made me want to Func’s more when I am writing C#.