simpleOpportunity :: Exchange
simpleOpportunity = Exchange (Map.fromList d)
    where
      d = [((A,B), 1.1), ((B,A), 0.95)]
simpleOpportunity :: Exchange
simpleOpportunity = Exchange (Map.fromList d)
    where
      d = [((A,B), 1.1), ((B,A), 0.95)]
simpleOpportunity = Exchange (Map.fromList d)
    where
      d = [((A,B), 1.1), ((B,A), 0.95)]