It is a fine start to support with a float128 type. :)

With vectors, there are around 20 tied to the x86 architecture iirc,
to whom's base types cover D equivalents of: byte, ubyte, short,
ushort, int, uint, long, ulong, float and double.  I think for
consistent naming convention, much like 'c' is used to denote complex
types, I think 'v' should be used to denote vector types.  For
example, the types available on x86 will be:

64bits:
vfloat[2], vlong[1], vint[2], vshort[4], vbyte[8]

128bits:
vdouble[2], vfloat[4], vlong[2], vint[4], vshort[8], vbyte[16],
vulong[2], vuint[4], vushort[8], vubyte[16]

256bits:
vdouble[4], vfloat[8], vlong[4], vint[8], vshort[16], vbyte[32]


For portability, vectors should be defined with the following logic:For example:

* vector size cannot be zero
* vector size must be a power of 2.
* if there is no hardware support for the vector type/size, then fall
back to static array type of same size.
* defining a vector without a size ie: vint foo;  will default the
size to zero, which will error.

That's all I can think of so far.