Ada Compiler abandons Instantiation of package passing overloaded operators - operator-overloading

Question

I want to instantiate a package and pass functions to it that overload operators in order to make a Generic Binary Search Tree. Here's the specifications.
bstgen.ads (snippet)
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Unchecked_Deallocation;
GENERIC
type Akey is private;
type TreeRecord is private;
with function "<"(K: in Akey; R: in TreeRecord) return Boolean;
with function ">"(K: in Akey; R: in TreeRecord) return Boolean;
with function "="(K: in Akey; R: in TreeRecord) return Boolean;
PACKAGE BSTGen IS
TYPE St10 IS NEW String(1..10);
TYPE TreePt IS PRIVATE;
PACKAGE EnumIO IS NEW Ada.Text_IO.Enumeration_IO(Akey); USE EnumIO;
driver.adb (snippet)
with Ada.Text_IO; use Ada.Text_IO;
WITH BSTGen;
PROCEDURE Driver IS
IP: Integer := 1;
TYPE Names IS (Resig,Keene,Marsden,Vuijic,Marcus,Gonzalez);
PACKAGE NamesIO IS NEW Ada.Text_IO.Enumeration_IO(Names);
type St10 is NEW String(1..10);
type Customer is
record Name: Names;
PhoneNumber: St10;
end record;
function "<"(K: in Names; R: in Customer) return Boolean is begin
return K < R.Name;
end "<";
function ">"(K: in Names; R: in Customer) return Boolean is begin
return K > R.Name;
end ">";
function "="(K: in Names; R: in Customer) return Boolean is begin
return K = R.Name;
end "=";
PACKAGE IntIO IS NEW Ada.Text_IO.Integer_IO(Integer); USE IntIO;
PACKAGE mybst is NEW BSTGen(Names,Customer,<,>,=); USE mybst;
R, Pt: TreePt;
Name: Names;
Phone: St10;
Status: Boolean;
BEGIN
R := CreateTree;
Pt := R;
However, when I try to compile, this is the output:
driver.adb:24:04: expect subprogram or entry name in instantiation of "<"
driver.adb:24:04: instantiation abandoned
bstgen.ads:19:53: expect discrete type in instantiation of "Enum"
bstgen.ads:19:53: instantiation abandoned
This includes a bunch of errors stating that driver.adb's methods are not visible, which is to be expected as the instantiation of mybst is abandoned. How do I fix this?

Answer 1

In bstgen.ads, you say
PACKAGE EnumIO IS NEW Ada.Text_IO.Enumeration_IO(Akey);
but in the generic formal part you said
type Akey is private;
which means that the compiler can assume very little about the actual type except that equality and assignment are available. It could be a record of hundreds of bytes; it certainly need not be an enumeration.
To ensure that Akey is an enumeration, you need to say
type Akey is (<>);
as in ARM12.5(13).
In driver.adb, you say
PACKAGE mybst is NEW BSTGen(Names,Customer,<,>,=);
which should read
PACKAGE mybst is NEW BSTGen(Names,Customer,”<“,”>”,”=“);