new Minus

[DanGrayson]

i6 : new Minus from {a,b,c}

o6 = -a

o6 : Expression of class Minus

An error message should be issued here, because the initializing list has length greater than 1.

[d-torrance]

Or should net(Minus) be updated to return -{a,b,c} instead?

[pzinn]

No,net works correctly, a Minus is supposed to be of length 1.
That being said I don't understand the original issue. There are plenty of "illegal" objects one can create using the "new" construction. The latter is low level and therefore allows (and should allow) to construct essentially anything.
For a given class, one can always create a high level constructor (e.g., hashTable for HashTable) that can do all kinds of checks as needed.

[mahrud]

i1 : new GradedModule from { blah => foo }

o1 = 0

o1 : GradedModule

i2 : peek oo

o2 = GradedModule{blah => foo}