Monthly Archives: August 2014

Using SQL Server to solve Einstein’s puzzles

Posted on August 23, 2014 by Dimitrios Kalemis

A particular category of logic puzzles have to do with the satisfaction of constraints. Among those are the so called “Einstein’s puzzles”, also called “zebra puzzles“. The first time I saw such a puzzle was about 10 years ago. I … Continue reading →

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How jectivity corresponds to morphisms

Posted on August 18, 2014 by Dimitrios Kalemis

“Jectivity” may or may not be a real word in the dictionary and my command of the English language is not adequate for me to make such a discussion. But “jectivity” is indeed a valid mathematical word and it concerns … Continue reading →

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Absolute URLs vs. relative URLs vs. protocol relative URLs

Posted on August 13, 2014 by Dimitrios Kalemis

Examples Absolute URL: http://yoursite.com/folder/subfolder/file.html Relative URL: /folder/subfolder/file.html Protocol relative URL: //anothersite.com/anotherfolder/anothersubfolder/anotherfile.html Tips Try to avoid absolute URLs. Try to use relative URLs for links inside your site. Try to use protocol relative URLs for links outside your site.

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Venn diagrams vs. Euler diagrams

Posted on August 12, 2014 by Dimitrios Kalemis

In Venn diagrams, all areas (subsets) are shown. Areas that contain no elements (empty subsets) are filled with black color. In Euler diagrams, only areas that contain elements (non-empty subsets) are shown. If we want to depict all areas, irrespectively … Continue reading →

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Arrow talk

Posted on August 10, 2014 by Dimitrios Kalemis

On the Stack Overflow site, I found a great question titled Monads vs. Arrows. Essentially the OP (original poster) asks: “… When should I use monads and when should I use arrows?”. I answered the question and since I believe … Continue reading →

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Cheat sheet for Monads in Haskell

Posted on August 2, 2014 by Dimitrios Kalemis

Let M be a Type Constructor, Functor, and Monad. As a Type Constructor, M can map a type a to the type M a. As a Functor, M can also map a function f to the function M f, using … Continue reading →

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The most significant FAQs about Haskell

Posted on August 1, 2014 by Dimitrios Kalemis

Question: Function application and composition versus bind (>>=) Answer: For the following discussion, a, b, and c are built in Haskell data types. We use normal function composition when we compose a function a -> b with a function b … Continue reading →

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