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Re: Making a new definition of Equal work with lists as well


Thank you, Bill and Jean-Marc, for your replies.

I'm afraid I didn't give a sufficiently general example in my question.
What I would like to do is to be able to get True/False results for
expressions as general as

{CL[2,3], 5, {CL[4,5], CL[2,2]}, x} == {CL[2,3], 8, {CL[6,7], CL[9,9]},
y}

that is, lists containing both CLs and other elements, and nested lists
etc.

Making Equal listable wouldn't work because I would then get also a
list (of booleans) as a result.

I think defining Equal for CL[a_, b_] could have "just worked" if Equal
for lists was internally defined to AND the Equal of all matching
pairs, something like

Equal[j_ListQ, k_ListQ]:=If[Length[j]!=Length[k], False,
And@@Table[Equal[j[[i]], k[[i]]], {i, 1, Length[j]}]

And I guess I could re-define it this way, but I wonder what the
built-in definition is, and what I stand to lose by overriding it like
that.

Thanks again,
-- Dan


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