Create an inverse of Tupper's self-referential formula where you can, given a drawing, find the corresponding value of K that draws that image.

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SQL practice tool

I find that online tools for practicing SQL queries are inadequate, they suffer from numerous problems that should be addressed by any (new) alternative.

Specific question sets, i.e. a decent collection of division problems A website that looks like it was rendered this century Insight into the dataset being tested against. If I was to build this I could imagine doing it using a Python back-end and I would build in a roll-back feature if the tool ever was to be extended to such a degree that one may practice directives such as UPDATE.

Nice to have the opportunity to load in one's own dataset.

Inspiration http://sqlfiddle.com/ http://sqlzoo.net/

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The developer app

Get a message (Tip of the day) each day with, for instance, hotkeys for your favorite editor/editors/programming languages.

Let users skip certain tips: "I already know this" so that it doesn't appear again. Use a Bloom-filter.

Let users select "Emacs", "Vim", "Git", etc.

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Create a Boolean Algebra interpreter in Common Lisp

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Implement an HTTP server with persistent connections in Haskell (look at STM)

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Use Markov chains to create lolcats

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Implement a Shell in Rust (posix grammar is here = http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3...)

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Implement various algorithms and data structures,

A-star Actor Model AVL Tree Binary Search Binary Search Tree Bloom-filter Breath-first iterative search Bucket/Radix sort Circular queue Closest pair HashMap In-place quicksort K-way merge Murmurhash Priority Queue Set Stack Union Find Vector (dynamic array)