`PrintFunction` should not duplicate terms when printing

[oflatt]

Printing a constructor looks like this:

(
  (Add 1 2) -> (Add 1 2)
 ...
)

I think it should look like:

(
  (Add 1 2)
)

For a function it can remain the same, or perferably be something like this to match proofs:

(
  (lower-bound (Add 1 2) 3)
)

[saulshanabrook]

Qs:

• for constructors will return value be canonical form?

feedback:

• for second one, this doesn't make that much sense if you can't use this in egglog

[oflatt]

@FTRobbin has a good point, print function currently gives you a term for that eclass, which may be different for different terms.

So maybe we want something like:

(
   (Add 1 2) -> e1
   (Add 2 1) -> e1
   (Add 3 4) -> e2
   ...
)

[saulshanabrook]

[oflatt]

Or maybe

(((Add 1 2)
   (Add 2 1))
 ((Add 3 4)))

Or

((EClass
   (Add 1 2)
   (Add 2 1))
 (EClass
    (Add 3 4)))

[oflatt]

@FTRobbin Suggests also something might be useful is print-eclass-contents

[oflatt]

Should there be print-function and print-constructor and we enforce you use the correct one?

Probably another separate issue

[oflatt]

Most popular proposal is to change it to look like this for constructors:

((EClass
   (Add 1 2)
   (Add 2 1))
 (EClass
    (Add 3 4)))

But no firm decision yet

[oflatt]

Broke out this issue into #819, #820, #822

This issue is now just about how to display print-function output for constructors.