Inferring Intersection Typings that are Equivalent to Call-by-Name and Call-by-Value Evaluations

We present a procedure to infer a typing for an arbitrary λ-term M in an intersection-type system that translates into exactly the call-by-name (resp., call-by-value) evaluation of M. Our framework is the recently developed System E which augments intersection types with expansion variables. The inferred typing for M is obtained by setting up a unification problem involving both type variables and expansion variables, which we solve with a confluent rewrite system. The inference procedure is compositional in the sense that typings for different program components can be inferred in any order, and without knowledge of the definition of other program components. Using expansion variables lets us achieve a compositional inference procedure easily. Termination of the procedure is generally undecidable. The procedure terminates and returns a typing if the input M is normalizing according to call-by-name (resp., call-by-value). The inferred typing is exact in the sense that the exact call-by-name (resp., call-by-value) behaviour of M can be obtained by a (polynomial) transformation of the typing. The inferred typing is also principal in the sense that any other typing that translates the call-by-name (resp., call-by-value) evaluation of M can be obtained from the inferred typing for M using a substitution-based transformation.

Portraits of Protestant Teens: a report on teenagers in major U.S. denominations

Religious participation -- Religious beliefs -- Faith, practices, and experiences -- Sharing faith -- Evaluations of church -- Moral views and risk behaviors -- Civic activities.

Occupational lead neurotoxicity: Improvement in behavioural effects after reduction of exposure.

To evaluate critical exposure levels and the reversibility of lead neurotoxicity a group of lead exposed foundry workers and an unexposed reference population were followed up for three years. During this period, tests designed to monitor neurobehavioural function and lead dose were administered. Evaluations of 160 workers during the first year showed dose dependent decrements in mood, visual/motor performance, memory, and verbal concept formation. Subsequently, an improvement in the hygienic conditions at the plant resulted in striking reductions in blood lead concentrations over the following two years. Attendant improvement in indices of tension (20% reduction), anger (18%), depression (26%), fatigue (27%), and confusion (13%) was observed. Performance on neurobehavioural testing generally correlated best with integrated dose estimates derived from blood lead concentrations measured periodically over the study period; zinc protoporphyrin levels were less well correlated with function. This investigation confirms the importance of compliance with workplace standards designed to lower exposures to ensure that individual blood lead concentrations remain below 50 micrograms/dl.