[MLton-user] Raw conversion of 32 bits into Real32.t

[Matthew Fluet]

>> MLton will flatten away some tuples so that they are never allocated 
>> on the heap.  I could imagine doing something similar with 
>> arrays/vectors of statically known size; it would effectively turn the 
>> array/vector into a tuple, which would be flattened.
>>
>> Unfortunately, in this particular example, where we are using the 
>> array to coerce between Word32.word and Real32.real, it wouldn't 
>> really work, since we're necessarily accessing multiple Word8.word 
>> elements at a time.
> 
> This approach sounds to me far preferable. I am confused by why 
> accessing word8 elements would preclude the optimization you described?

Because the Pack{Real32,Word32}Little functions are accessing multiple, 
contiguous elements of the array.  So, one would need to ensure that the 
elements are laid out in a contiguous manner and that the operations 
that accessed the elements could be typed correctly.  The type systems 
we have don't really allow that to be expressed; the Pack* functions are 
primitives that get to be assigned the appropriate type.