Technical Report: DCC-98-12

Counting a type's principal inhabitants

 Sabine Broda and Luís Damas

DCC-FC & LIACC, Universidade do Porto
R. do Campo Alegre 823, 4150 Porto, Portugal
Phone: 351 22 6078830, Fax: 351 22 6003654
E-mail: {sbb,luis}}
  December 1998


We present a Counting Algorithm that computes the number of $\lambda$-terms in $\beta$-normal form that have a given type $\tau$ as a principal type and produces a list of these terms. The design of the algorithm follows the lines of Ben-Yelles' algorithm for counting normal (not necessarily principal) inhabitants of a type $\tau$.