[r6rs-discuss] "Unspecified" (naming)

[John Cowan]

Jonathan A Rees scripsit:

> I believe "void" was coined by Algol 68 as a *type* having only one  
> value. 

Just so:  http://vestein.arb-phys.uni-dortmund.de/~wb/RR/rr213.html#2131h

> I don't know what, if anything, [S]ML calls the value of its unit type -  
> maybe "()" or "null".

It is indeed written "()" and is pronounced "unit", the same as the type.
This ambiguity in the spoken form does not seem to cause problems in
practice.

> Of course, in 1957 this thing was called "nil", and McCarthy may be  
> the most respectable precedent we have available.

However, there are at least some Scheme programmers who use "nil" as
a spoken reference to (), since it is only 1/4 as long as "the empty
list".  (I polled #scheme yesterday.)

-- 
Do what you will,                       John Cowan
   this Life's a Fiction                cowan at ccil.org
And is made up of                       http://www.ccil.org/~cowan
   Contradiction.  --William Blake