This report gives a simple implementation of A. Baars and S.D. Swierstra’s “Typing Dynamic Typing” [5] using modern (GHC) Haskell features, and shows that the technique is especially beneficial in a compositional setting, where parts of the expression are defined separately. Evaluating expressions that are represented as algebraic data types typically requires using tagged unions to represent v...

Dynamic languages are praised for their flexibility and expressiveness, but static analysis often yields many false positives and verification is cumbersome for lack of structure. Hence, unit testing is the prevalent incomplete method for validating programs in such languages. Falsification is an alternative approach that uncovers definite errors in programs. A falsifier computes a set of input...

Entities in engineering design databases need to evolve in both structure and behavior. Such a need is not well addressed by object-oriented data models based on the class concept. On the contrary, models that are based on the prototype concept allow dynamic object evolution but they do not have the abilities for object classification and strong typing supported by models that have classes. In ...

Gradual type systems meld dynamic typing with optional static types, moderating between the two with statically inserted casts. Casting is the éminence grise of such systems — it enables swift detection of type errors in dynamic code without enforcing runtime checks throughout a program, and in combination with blame tracking it allows such errors to be traced to their origin. However, such cas...

Several programming languages are beginning to integrate static and dynamic typing, including Racket (formerly PLT Scheme), Perl 6, and C# 4.0 and the research languages Sage (Gronski, Knowles, Tomb, Freund, and Flanagan, 2006) and Thorn (Wrigstad, Eugster, Field, Nystrom, and Vitek, 2009). However, an important open question remains, which is how to add parametric polymorphism to languages tha...

A split Hopkinson pressure bar (SHPB) system with a special shape striker has been suggested as the test method by the International Society for Rock Mechanics (ISRM) to determine the dynamic characteristics of rock materials. In order to further verify this testing technique and microscopically reveal the dynamic responses of specimens in SHPB tests, a numerical SHPB test system was establishe...