Mutations and type usage in Ada

["Derek M. Jones" <derek@_NOSPAM_knosof.co.uk>]

All,

To what extent will Ada type checking cause mutated
programs, where some of the variables have been changed,
to be flagged at compile time?

I have had people tell me stories of mutated Fortran and C
programs successfully compiling and passing all the test
cases (I have had no luck tracking down papers giving details;
most papers discuss what happens when operators are changed,
statement deleted, etc; I am interested in what happens when
just the variables are changed).

Does anybody know of any mutation work with Ada that involves
changing the variables?

Whether or not a change of variable will result in a compile
time error will depend on the extent to which a program makes
use of the Ada type system.  For instance, if all my variables
have type integer then the switching them around is unlikely
to generate a compile time message.

Does anybody know of any measurements of Ada source that have looked
at how 'strongly' they are typed?  That is, do many developers
use integer everywhere, or do that always create a new type for
everything?

My experience with Pascal (yes, Pascal is not Ada) was that many
programmers would not spend the time needed to think about the
type that needed to be created.  Perhaps some of these people have
been sucked into Ada and managed to avoid the 'type safety' thought
police :-)