Empty Frames in SHARP APL
Roland H. Pesch

Introduction
Recapitulation: earlier attempts at solutions
  •   Prototypes
  •   Shape Expressions
Surrogate arguments
  •   An Operator Calculus
  •   Overtake
  •   Comparison, evaluation, extension
Nil use with surrogate arguments
  •   Nil
  •   No nils in results
  •   How nils are used
  •   Required domain extensions
  •   Fill or type
Conclusion
 
References