Why "unit"?

[Raphael Collet]

Harmon Nine wrote:
> Why is “unit” (as opposed to, say, “frozboz”) the non-descript value to 
> bind a variable to when any atom would do?  Is there a history behind 
> this, e.g. was it taken from another language?

I am not sure, but I think it first appeared in functional languages. 
Functions that do some side effects, but don't return a result, just 
return "unit".  It is used as a value with no semantics.

The name "unit" comes from the fact that the type of "unit" only has one 
possible value.  If you write the type Unit as a set of values, you have 
Unit={unit}.

Cheers,
raph