some attempts to speed things up class s_let:   keep <vars> in a set gen_vcase():   support else clauses unifier.add():   speed up tests solve():   u3 stuff isn't needed instantiate_constraint():   correctly handle eqs with >1 variable lookup():   speed up logic typer.go():   find_records(): to be removed
some attempts to speed things up
class s_let:
  keep <vars> in a set
gen_vcase():
  support else clauses
unifier.add():
  speed up tests
solve():
  u3 stuff isn't needed
instantiate_constraint():
  correctly handle eqs with >1 variable
lookup():
  speed up logic
typer.go():
  find_records(): to be removed


samrushing/irken-compiler,samrushing/irken-compiler,samrushing/irken-compiler,samrushing/irken-compiler