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From Matt Benson <>
Subject Re: [functor] Patch for FUNCTOR-14, new Generators and Ranges
Date Tue, 05 Jun 2012 15:08:56 GMT
Hi, Bruno!

  I have some questions:

1.  Why are a Range's type and step-type potentially different
(different type variables, etc.)?
2.  Why, if it is a Generator's responsibility to generate items
subsequent to the lower endpoint, is the step part of the range at
all?  Based on [1], which definition of "range" are we attempting to
represent?  The current code seems to implement definition 2 and
*part* of definition 3, deferring the rest to a corresponding
Generator.  Settling the question of whether [functor]'s Range is a
"2-range" or also a "3-range" would seem to dictate our action:  do we
move the step to the generator, or do we make Range calculate each
item (in which case would it be simpler for Range to implement

I am by no means an FP or any other type of expert, so feel free to
show me why I'm wrong on a given point!



On Mon, Jun 4, 2012 at 11:59 PM, Bruno P. Kinoshita
<> wrote:
> Hi all,
> I've finished a patch for FUNCTOR-14, regarding the Generators API in [functor]. I'd
like to hear what others think about what was done before attaching the patch to JIRA:
> - Didn't change the Generator interface. Although I commented in the issue about removing
the stop() and isStopped() methods and moving to a different interface, it would require a
major refactoring, as many other generators are built upon this idea.
> - Created IntegerGenerator, LongGenerator, FloatGenerator, DoubleGenerator and CharacterGenerator.
Didn't implement a DateGenerator as it would require more time and a discussion on how to
use days, months, years, days of week, etc.
> - Introduced Ranges, with the following initial ranges: IntegerRange, LongRange, FloatRange,
DoubleRange and CharacterRange. This API is quite similar to other existing APIs, with the
difference that you can specify the step (like ranges in Matlab)
> - The generators that use numbers (there are many other generators, like GenerateWhile,
GenerateUntil, etc) use ranges to create the series. The objects are created only when the
generator is executed, calling a procedure. Like in python, but instead of retrieving the
value with a 'yield' statement, we give a procedure to be executed using the value created.
> - Included tests to cover the changes.
> - Updated web site examples.
> All the tests passed, no checkstyle/pmd/findbugs errors. The character range/generator
is a very simple, and there are some operations with double/float in the ranges and generators.
I keep my code mirrored in github too, in case someone prefers reading it there
> Let me know what you think about it :-)
> Thank you in advance!
> Bruno P. Kinoshita
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