nonexhaustive_nested.chr

:- module(nonexhaustive_nested, [classify/1]).
:- chr_type color ---> red ; green ; blue.
:- chr_type pair ---> pair(color, color).
:- chr_constraint classify/1.
:- function pick(pair) -> int.
pick(pair(red, _)) -> 1.
pick(pair(green, _)) -> 2.
classify(R) <=> R is pick(pair(red, blue)).