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A comment on Evolving Java Without Changing the Language . Parent comment

Re:Evolving Java Without Changing the Language by wiggles on Thursday October 22, 2009 @12:54PM (#897082)
Have you ever written any ML/Haskell?

It's nearly impossible to get past the type system unless your code is correct, especially for small chunks of code.

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Re:Evolving Java Without Changing the Language by jrockway on Thursday October 22, 2009 @01:46PM (#897255)
No, he is right; however, Java has the exact problem.

The place where this code will screw up is in the logic of the comparison routine. It will be difficult for the types of x and y (or a and b in the Java example) to be wrong, but it is easy to say:

    compare (length x) (length x)
or

    compare (length y) (length x)
instead of

    compare (length x) (length y)
Your tests will catch this, though.
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