AN APL MACHINE.
Abstract
The dissertation proposes a design for a machine structure which is appropriate for APL and which evaluates programs in the language efficiently. The approach taken is to study the semantics of APL operators and data structures rigorously and analytically. A compactly representable standard form is exhibited for select expressions, which are composed of operators which alter the size and ordering of array structures. In addition, a set of transformations is presented sufficient to derive the equivalent standard form for any select expression. The standard form and transformations are then extended to include expressions containing other APL operators. By applying the standard form transformations to storage access functions for arrays, select expressions in the machine can be evaluated without having to manipulate array values; this process is called beating. Drag-along is a second fundamental process which defers operations on array expressions, making possible simplifications of entire expressions through beating and also leading to more efficient evaluations of array expressions containing several operations. The APL machine consists of two separate sub-machines sharing the same memory and registers. The D-machine applies beating and drag-along to defer simplified programs which the E-machine then evaluates. The major machine registers are stacks, and programs are organized into logical segments. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1970
- Accession Number
- AD0706741
Entities
People
- Philip S. Abrams
Organizations
- Stanford University