I just created D bindings[1] for the MPFR library[2].

It also contains a D type[3] that wraps call to the library.

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1. http://code.dlang.org/packages/deimos-mpfr
2. http://www.mpfr.org/
3. https://github.com/gchatelet/deimos-mpfr/blob/master/source/mpfrd.d