Harry J. Saal

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The foundations of capability schemes are critically examined. The context free utilization of capabilities once acquired is shown to be inconsistent with both least privilege norm and information flow requirements. An enhanced Capability Vector mechanism which pre-confines the set of capabilities with which a given capability can be combined is proposed.(More)
The design of a high performance APL system is presented along with an evaluation of the performance improvement measured on a partial implementation. The system contains a compiler which translates APL into the instructions of a virtual APL machine. Numerous special techniques suitable for optimized interpretation of this virtual machine entirely in(More)
Some results of a study of the static usage of features of the APL language is presented. We compare several characterizations of APL programs with previously measured FORTRAN data, and discuss the significant differences observed. The verity of popular rumors and intuitions about APL programs is also examined. APL users appear to take advantage of the(More)
The amount of extravascular immunoglobulin deposits in the synovial membrane of patients with osteoarthritis and rheumatoid arthritis was studied in comparison with that of patients suffering from non-joint diseases. Immunoglobulin deposits were immunostained using the three-layer immunoperoxidase method. The staining results were quantified with the help(More)
APL in its present interpretive implementations provides an ideal tool for the development of programs. The interpretive overhead, however, often prohibits the running of large production programs. Our results indicate that the overhead involved in checking type and size compatibility of the arguments of APL primitive functions during execution can be(More)
We present a technique for the compile-time determination of the syntactic attribute of names essential for the development of a compile-time parser for APL. The method is applicable to a large class of APL programs namely, programs which do not utilize certain features of the language allowing dynamic changes in the syntactic meaning of program statements.(More)
Existing implementations of the APL language are generally referred to as "interpretive". APL users rely on system behavior of an interpretive nature, such as "desk calculator mode" debugging, and modern interpreters retain that external view even though internal interpreter organization is highly optimized. Increased use of APL has led to many requests for(More)