Showing posts from June, 2015

SHA1 compile time checked literals: F# vs Nemerle vs D

I've always been interested in metaprogramming. Sooner or later, I'm starting to feel constrained within a language without it. F# is a really nice language, but I'm afraid I'd have got bored with it if it'd not have Type Providers, for example. Why metaprogramming is so important? Because it allows changing a language without cracking the compiler. It allows making things which seemed to be impossible to implement.

I'm dealing with cryptography hashes a lot at work, nothing rocket since, just MD5, SHA-1 and so on. And I write tons of tests where such hashes are used in form of string literals, like this:

The problem with this code is that the compiler cannot guarantee that the hex string in the last line represents a valid SHA-1. If it does not, the test will fail at runtime for a reason it's not intended to.

OK, now we can formulate our task: provide a language construct to enforce a string literal being a valid SHA-1 hexadecimal, at compile time. We wil…

Fib: C++, C# and GDC

As a reference implementation, I added C++ one:

It's execution time is 1.33 seconds, which surprisingly is not the best result so far.
A C# version:

Also, I compiled this D code with GDC compiler and it executed in 990 ms, which is the best result:

D (GDC) - 0.990C# - 1.26D (DMD) - 1.3C++ - 1.33F# - 1.38Nemerle - 1.45Rust - 1.66Go - 2.38Haskell - 2.8Clojure - 9Erlang - 17Ruby - 60Python - 120
Unfortunately, I have not managed to compile the D code with LDC compiler, it returns the following error:
Building: DFib (Release) Performing main compilation... Current dictionary: d:\git\DFib\DFib D:\ldc2-0.15.2-beta1-win64-msvc\bin\ldc2.exe -O3 -release "main.d"   "-od=obj\Release" "-of=d:\git\DFib\DFib\bin\Release\DFib.exe" LINK : fatal error LNK1181: cannot open input file 'kernel32.lib' Error: C:\Program Files (x86)\Microsoft Visual Studio 12.0\VC\bin\link.exe failed with status: 1181 Exit code 1181