Motivation and considerations:
- A Scryer certainly needs a raven. Ravens are among the most
intelligent animals on earth.
- When writing Prolog programs, a few strokes are often enough.
- Purple is the colour most associated with magic and royalty,
indicating the almost surreal and pure features provided by Scryer,
in the lineage of Marseille Prolog.
- The shape of the silhouette looks a bit like an "S" for "Scryer".
- A square which surrounds the image is traditionally associated with
finishing a proof (square, Latin "quadratum", has the same starting
letters as "quod erat demonstrandum").
I call this raven: *Cryer*. Cryer is an archaic spelling for "crier",
an officer who makes public announcements in a court of justice.
The Prolog top-level likewise makes announcements about what is true.
This is useful to generate keys and initialization vectors
from suitable input keying material, so that future predicates
for symmetric encryption can be used with appropriate parameters.
This is useful to establish shared secrets, using ECDH key exchange.
Note that CLP(ℤ) goal expansion is currently disabled due to #445,
and this slows down the computations considerably for the time being.
library(clpz) implements declarative integer arithmetic.
The most important predicates for reasoning about integers are:
(#=)/2 equality
(#\=)/2 disequality
(#<)/2 less than
(#>)/2 greater than
(#=<)/2 less than or equal to
(#>=)/2 greater than or equal to
In addition, the library provides several global constraints, such as
all_distinct/1 and global_cardinality/2, and reification predicates
that reflect the truth values of constraints into integer variables.
Enumeration predicates such label/1 and labeling/2 can be used to
search for solutions over finite domains.
Almost all Prolog programs also reason about integers. Therefore, I
recommend to add this library to your .scryerrc configuration file so
that declarative integer arithmetic is available in all your programs.
More information about CLP(ℤ):
https://www.metalevel.at/prolog/clpz
Enjoy!
