As a reference, here is the corresponding cyclic-structure-comparison
example from a message about E:
? define tight := [1, tight, "x"]
# value: [1, ***CYCLE***, x]
? define loose := [1, [1, loose, "x"], "x"]
# value: [1, ***CYCLE***, x]
? tight == loose
# value: true
? def map := [tight => "foo"]
# value: [[1, ***CYCLE***, x] => foo]
? map[loose]
# value: foo
Internally, tight and loose have very different representations.
However, when both cycles are unwound, they represent the same
infinite tree. One could say that tight's representation of this
tree is more tightly wound than loose's representation. However,
this difference is only in the implementation, not in the
semantics. The value of tight and loose is only the infinite tree
they represent. If these trees are the same, then tight and loose
are ==.
Notice that loose prints out according to the tightest winding
of the tree it represents, not according to the cycle by which
it represents this tree. Only the tightest winding is finite and
canonical.
-- ?!ng