PrimeTables

Multiplication table of N prime numbers

Running the project

Requirements

• Elixir 1.4.2 installed on the build machine
• A terminal

Building the project

git clone git@github.com:svarlet/PrimeTables.git
cd ./PrimeTables
MIX_ENV=PROD mix escript.build

Running the program

./prime_tables.bin -n <number_of_primes>

./prime_tables.bin -n 10
   |   2 |   3 |   5 |   7 |  11 |  13 |  17 |  19 |  23 |  29
 2 |   4 |   6 |  10 |  14 |  22 |  26 |  34 |  38 |  46 |  58
 3 |   6 |   9 |  15 |  21 |  33 |  39 |  51 |  57 |  69 |  87
 5 |  10 |  15 |  25 |  35 |  55 |  65 |  85 |  95 | 115 | 145
 7 |  14 |  21 |  35 |  49 |  77 |  91 | 119 | 133 | 161 | 203
11 |  22 |  33 |  55 |  77 | 121 | 143 | 187 | 209 | 253 | 319
13 |  26 |  39 |  65 |  91 | 143 | 169 | 221 | 247 | 299 | 377
17 |  34 |  51 |  85 | 119 | 187 | 221 | 289 | 323 | 391 | 493
19 |  38 |  57 |  95 | 133 | 209 | 247 | 323 | 361 | 437 | 551
23 |  46 |  69 | 115 | 161 | 253 | 299 | 391 | 437 | 529 | 667
29 |  58 |  87 | 145 | 203 | 319 | 377 | 493 | 551 | 667 | 841

Conclusion

I am pleased with

• The time I took beforehand to do some research before coding (read this paper)
• Implementing a very fast prime number generator thanks to my research
• Using property based testing to have extremely high test coverage on the prime numbers generation
• Continuous integration with Travis CI (check it there)
• Simple pretty printing
• TDD approach
• Small scoped commits

Things I'm not happy with

• The prime generator can be further optimized by considering odd numbers after 2.
• The prime generator can be further optimized by relying on a priority queue rather than a Map.
• There is no test coverage for command line option parsing or pretty printing
• DONE I would like to refactor the prime number generator to extract my Sieve datastructure to its own file
• The pretty printing part feels hacky because I did not give it much thought beforehand
• DONE A bunch of minor things which are not right (useless function clause, def/defp, ...)