Removed ~10000 hack in function idx that can lead to inconsistencies
when unifying terms with a large number of abstractions.
Sep2 = Main +
consts sep :: 'a list => 'a => 'a list
recdef sep "measure length"
"sep (x#y#zs) = (%a. x # a # sep zs a)"
"sep xs = (%a. xs)"
end