Re: Community Input for the Maintenance and Revision of the Ada Programming Language

["G.B." <bauhaus@notmyhomepage.invalid>]

On 11.08.17 03:31, Randy Brukardt wrote:
> Speaking of evil, anonymous types are evil. Why is it hard to declare a
> record type for this purpose?

A record is mutable, a tuple isn't meant to be mutable
(i.e., can't update it's components). Also, it is harder
to start from good types and names than to use a continous
improvement process that finds them.

A tuple language will first let programmers write

    return Integer, Float,
or
    -> (Int, Float)
or
   int, float function;

and then let them use these values "generically": anything that
takes an integer and a floating point value will work:
argument pattern matching, or referring to Fst and
Snd component using built-in ".0" and ".1" suffix notation.
It then does not matter whether the integers and FPT values
really are of types (apples, prices) or (oranges, weight)...
  
It is convenient.

It is prone to logical errors, because it'll make lazy
programmers stop making good use of the type system, i.e.
it eases accidentally mistaking apples for oranges,
or price for weight, IOW make reasonably errors.

It is, therefore, a very viable scheme of language based
supportbusiness.



OTOH, if (int, float) tuples used in the implementation
of an ADT only, then the convenience might loose some of
the disadvantages of depending on tuples.