# CDR 5: Sub-interval Numerical Types for Common Lisp

## Author / Submitter

Marco Antoniotti

## Abstract / Rationale

When working on numerical algorithms it is sometimes useful to further
constrain the types of certain values to sub-intervals of the usual
types present in Common Lisp. A typical example is that of indices
running over the dimensions of an array: such integers values should
not be negative. While several Common Lisp implementations already
have certain special "sub-interval" type specifiers that can be used
in implementation dependent code, it seems natural and relatively
uncontroversial to propose a set of specialized types that codify
usual mathematical numerical sets and intervals. This document puts
forward such a proposal.

## The Document

## Status

Final

## Previous Versions

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This page last modified: April 12, 2008