[erlang-questions] BSON parsing?
Richard A. O'Keefe
Fri May 16 00:44:53 CEST 2014
On 15/05/2014, at 11:35 PM, Loïc Hoguin wrote:
> Erlang doesn't have a representation for NaN, +infinity and -infinity.
Does anyone know why?
I've used Smalltalk systems which say "If non-IEEE arithmetic
was good enough for Granddad, it's good enough for me. SNIFF!"
and Smalltalk systems which say "Standard since 1985, available
everywhere, even on IBM z/Series, what earthly excuse could
there be for NOT presenting IEEE arithmetic?"
And the ones that don't hide infinities and NaNs turn out to be
easier to use.
Well, if I have straightforward numeric code, I'm going to
write it so that infinities and NaNs don't happen, so the
only downside to being nonstandard is the extra run-time cost.
But in fact very little numeric code is _that_ straightforward.
Using a Smalltalk that respects the standard, I can take working
numeric code in C or Fortran and convert it with very little
effort and it will do the SAME thing. Using a Smalltalk that
does not respect the standard, I have to analyse every
operation to make sure that it will work.
In fact my own Smalltalk library includes some vectorised
operations on specialised arrays, and it really would NOT
be safe to switch from an Array that happens to hold
FloatE objects to a FloatEArray if the arithmetic could be
different in any way.
Conversely, if I have some numeric code written in Erlang,
it would be nice to be able to translate it to C and link
it in. But making floating point semantics *different* in
Erlang and C makes this rather dangerous.
Is Erlang running these days on *any* hardware platform
that doesn't have IEEE arithmetic?
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