Product Perfect

**Focal** is a high-level programming language designed for numerical computing. It was developed by Yannis Assael and first released in 2014. Focal is based on the Julia programming language, but it has been optimized for numerical computing. Focal is open-source software and is available under the MIT license. **References:** * [Focal homepage](https://focal.dev/) * [Focal documentation](https://focal.dev/docs/) * [Focal on GitHub](https://github.com/focallang/focal)

Ask the right questions secure the right Focal talent among an increasingly shrinking pool of talent.

First 20 minutes

General Focal app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Focal application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you describe the basic structure of a Focal program?

A Focal program is structured into sections. Each section contains a series of statements. The sections include the DATA section, the PROCEDURE section, and the END section. The DATA section is used to declare variables and constants. The PROCEDURE section contains the main logic of the program. The END section signifies the end of the program.

What are the data types supported by Focal?

Focal supports several data types including integer, real, complex, logical, and character.

Describe the difference between a Focal procedure and a function.

A procedure in Focal is a block of code that performs a specific task and does not return a value. On the other hand, a function is a block of code that performs a specific task and returns a value.

How would you handle errors in Focal?

Focal provides several error handling mechanisms. One of them is the use of the ON ERROR statement which allows you to specify what should happen when an error occurs. Another is the use of the TRY...CATCH...FINALLY construct which allows you to catch and handle exceptions.

What are the control structures available in Focal?

Focal provides several control structures including IF...THEN...ELSE, FOR...NEXT, WHILE...DO, and CASE...OF.

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What you’re looking for early on

Does the candidate have a strong understanding of Focal programming language?

Has the candidate demonstrated problem-solving skills?

Is the candidate able to communicate effectively?

Does the candidate show a willingness to learn new technologies and adapt?

Next 20 minutes

Specific Focal development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

Describe the difference between a local and a global variable in Focal.

A local variable in Focal is a variable that is declared within a procedure or a function and is only accessible within that procedure or function. A global variable, on the other hand, is a variable that is declared outside of any procedure or function and is accessible throughout the entire program.

How would you implement recursion in Focal?

Recursion in Focal can be implemented by having a procedure or a function call itself. This is typically done to solve problems that can be broken down into smaller, similar problems.

What are the string manipulation functions available in Focal?

Focal provides several string manipulation functions including CONCAT (for concatenating strings), SUBSTR (for extracting a substring), LENGTH (for getting the length of a string), and REPLACE (for replacing a part of a string with another string).

Describe the difference between pass-by-value and pass-by-reference in Focal.

In pass-by-value, the actual value of the argument is passed to the function. Any changes made to the argument inside the function do not affect the original value. In pass-by-reference, a reference to the argument is passed to the function. Any changes made to the argument inside the function affect the original value.

How would you create and use an array in Focal?

An array in Focal can be created using the DIM statement. The elements of the array can be accessed using their indices. The indices start from 1.

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At this point, a skilled Focal engineer should demonstrate strong problem-solving abilities, proficiency in Focal programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Focal.

What does the following code do?
public static void main(String[] args) { System.out.println('Hello, World!'); }
This code prints the string 'Hello, World!' to the console.
What will be the output of the following code?
public static void main(String[] args) { int a = 5; int b = 10; System.out.println(a + b); }
The output will be 15, which is the sum of 5 and 10.
What does the following code do?
public static void main(String[] args) { List list = new ArrayList<>(); list.add('Apple'); list.add('Banana'); list.add('Cherry'); for(String fruit : list) { System.out.println(fruit); } }
This code creates a list of fruits and then prints each fruit in the list to the console.
What does the following code do?
public static void main(String[] args) { Thread thread = new Thread(() -> { System.out.println('Hello, World!'); }); thread.start(); }
This code creates a new thread and runs a task in that thread which prints 'Hello, World!' to the console.

Wrap-up questions

Final candidate for Focal Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Focal application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What are the file handling capabilities of Focal?

Focal provides several file handling capabilities including opening a file for reading or writing, reading data from a file, writing data to a file, and closing a file.

Describe the difference between a static and a dynamic array in Focal.

A static array in Focal is an array whose size is fixed at compile time. A dynamic array, on the other hand, is an array whose size can be changed at runtime.

How would you implement object-oriented programming in Focal?

Focal does not natively support object-oriented programming. However, it is possible to implement some aspects of object-oriented programming in Focal using structures and procedures.

Focal application related

Product Perfect's Focal development capabilities

Beyond hiring for your Focal engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Focal projects, and can engage in multiple capacities.

Focal Consultive assessments

Focal Application Conversion Assessment Focal Application Integration Assessment Focal Data & Database Integration Assessment

Custom Focal development projects

Custom Focal App Conversion Focal Custom App Development Process App UI Design for Focal Facelifts

Hiring guide for Focal Engineers

Focal Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

What you’re looking to see on the Focal engineer at this point.

Focal Consultive assessments

Custom Focal development projects