mike clemow wrote: > Troy, > > As a Java chimp embarking on the Haskell journey myself, I'd be > interested in hearing about specific ways that learning Haskell has > changed the way you program Java. How do you employ the "very > interesting concepts" that you have learned through your study of > Haskell in your Java programming? Do you employ them at all? _Can_ > they be employed in Java? Has it made you a better Java programmer? > > Cheers, > Mike
I reinvented functional programming when I was using Java rather than Haskell making me use Java more succintly. I knew something was seriously wrong with imperative programming and Java's type system all those years I spent working on the implementation for IBM. I was pleased to learn that Haskell incorporated many of my ideas (and more) - validating my original suspicions. The fact that many of the concepts in Haskell I had already "invented" made the language easy for me to learn (as in, "oh yeah of course that makes perfect sense" in response to discover monads). I produced many Java projects in an attempt to demonstrate what I thought was wrong, but few of them remain due to loss of interest. http://jtiger.org/ http://code.google.com/p/pure-functional-java/ In regard to the original question, 'What are the mysterious "side effects" which are avoided by using Haskell, which everyone talks about? Null pointers?', my response is "yes". Looking at a NullPointerException (NPE), these exist because of the imperative nature of the code; with explicit order of evaluation and potential side-effects. In an attempt to highlight the absurdity of the fact that a NPE even exists, I like to tell people that "NPEs occur when you write a program that says, 'give me the something that is not there yet'". Now, if you have read Stephen Hawking's Brief History of Time and the chapter titled, Arrow of Time, you will know that "the arrow of time will not reverse". How absurd it is to suggest otherwise by imperative programmers! Simply, a programming language that allows an expression of "give me the non-existent something" contains a logical absurdity. let p(something) = something exists let q(something) = something is non-existent let r = p ? ¬q let s = p ? q therefore r therefore s but r ? ¬s !! I have long considered (well before I knew about Haskell) formulating a more concrete proof that imperative programming contains many logical absurdities. Remember, forall software. software is based on the lambda calculus. I believe that you can prove this. Tony Morris http://tmorris.net/ _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
