Ballerina range expression implemenation problem with Iterator object. Incompatible types error - wso2

Question

I'm trying to understand the way this example code works in the Range Expressions Example on Ballerina By Example. I'm using Ballerina 1.0.5.
I'm facing an issue at the line } iterableObj = 25 ..< 28; where I get an incompatible types error. I've tried to replicate the type that it needs by trying various things including switching between exclusive and inclusive record descriptors but I can't seem to be able to figure it out. I'm also new to this language.
When I run the code below. It gives me the error as follows:
Error
error: .::range_expressions.bal:20:21: incompatible types: expected 'object { public function __iterator () returns (object { public function next () returns (record {| int value; |}?); }); }', found 'object { public function next () returns (record {| int value; |}?); }'
Code
import ballerina/io;
public function main() {
io:println("foreach for 25 ... 28");
foreach int i in 25 ... 28 {
io:println(i);
}
io:println("\nforeach for 25 ..< 28");
foreach int i in 25 ..< 28 {
io:println(i);
}
abstract object {
public function __iterator() returns
abstract object {
public function next() returns record {|int value;|}?;
};
} iterableObj = 25 ..< 28; // facing an issue here
abstract object {
public function next() returns (record {|int value;|}?);
} iterator = iterableObj.__iterator();
io:println("\niterable object for 25 ..< 28");
while (true) {
record {| int value; |}? r = iterator.next();
if (r is record {| int value; |}) {
io:println(r.value);
} else {
break;
}
}
}
Misc. Info
I'm having a similar issue with the example Iterable Objects. I get an incompatible types error when I try to execute the code in that example as well and I think the underlying problem is the implementation of iterator objects. I don't think I should post the code here or the question will seem far too long.
Per the info:
Any subtype of abstract object {public next() returns record {| T value; |}?;}, is called Iterator.
Main Question
I've gone through what I can glean from the language specifications and I can't seem to figure this out. Could you please tell me how to fix this error and if possible, a small explanation of the way the example works?

Answer 1

I think the issue is that the code you are trying to implement is a new addition in 1.1.0 release, 1.1.0 was release on 19/12/2019.
You can either download the 1.1.0 or use the version selector in the web site to get pre 1.1.0 documentation. There should be a version selector in top right of the webpage, from there you can select 1.0 to get the documentation for 1.0.5 compiler.
Edit:
There seems to be a bug in the website that prevent you from accessing versioned Ballerina by examples. Please use the source code of them for now. https://github.com/ballerina-platform/ballerina-lang/tree/release-1.0.5/examples