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Parlog++ is a concurrent logic programming language developed in the 1980s, an extension of Parlog, which incorporates object-oriented programming features. It was created by Steve Gregory at Imperial College London as a research project into parallel computing. The language combines the advantages of logic programming with parallel execution and message-passing between objects. Its syntax and semantics are similar to Prolog but include additional constructs for concurrency and communication. Despite its innovative approach, Parlog++ did not gain widespread use outside academia (Gregory S., "Parallel Logic Programming in PARLOG: The Language and Its Implementation", Addison-Wesley Publishing Company, 1987).

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

First 20 minutes

General Parlog++ app knowledge and experience

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

How would you define the term 'backtracking' in Parlog++?

Backtracking in Parlog++ refers to the process of returning to a previous state when a certain path of execution doesn't lead to a solution. It's a key part of Parlog++'s logic-based execution model.

What are the fundamental principles of Parlog++?

Parlog++ is based on logic programming, parallel execution, and message passing. These principles allow it to effectively handle problems that require concurrent processing and complex logic.

Describe the difference between 'and-parallelism' and 'or-parallelism' in Parlog++.

'And-parallelism' refers to the simultaneous execution of subgoals of the same goal, while 'or-parallelism' refers to the simultaneous execution of different solutions for the same goal. Parlog++ supports both types of parallelism.

How would you handle deadlock in Parlog++?

Deadlock prevention in Parlog++ can be achieved using various techniques such as avoiding circular waits, preventing hold and wait, etc. The choice of technique depends on the specific structure and requirements of the program.

What are the key features of Parlog++'s syntax?

Parlog++'s syntax features include a logic-based declarative style, the use of 'and'/'or' for parallel execution, the use of guards for conditional execution, and the use of channels for communication between processes.

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What you’re looking for early on

Does the candidate have a solid understanding of Parlog++?

Has the candidate demonstrated problem-solving skills?

Is the candidate able to communicate effectively?

Does the candidate have experience with similar projects or tasks?

Next 20 minutes

Specific Parlog++ 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 'deterministic' and 'nondeterministic' execution in Parlog++.

Deterministic execution in Parlog++ means that the outcome of the program is fully determined by the inputs. Nondeterministic execution, on the other hand, means that the program can have different outcomes for the same inputs, depending on the order and timing of execution.

How would you handle exceptions in Parlog++?

Parlog++ does not have built-in support for exception handling, so exceptions need to be handled manually. This can be done by implementing error-checking code within the program, and using conditional statements to handle different error conditions.

What are the typical use cases for Parlog++?

Parlog++ is typically used for problems that require parallel processing and complex logic, such as artificial intelligence, simulation, and optimization problems. Its logic-based programming model makes it well-suited for these types of problems.

Describe the difference between 'synchronous' and 'asynchronous' message passing in Parlog++.

Synchronous message passing in Parlog++ means that the sender waits for the receiver to receive the message. Asynchronous message passing, on the other hand, means that the sender continues execution without waiting for the receiver.

How would you optimize a Parlog++ program for performance?

Performance optimization in Parlog++ can involve various techniques such as minimizing communication between processes, optimizing the use of parallelism, and reducing the complexity of the logic. The choice of techniques depends on the specific structure and requirements of the program.

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At this point, a skilled Parlog++ engineer should demonstrate strong problem-solving abilities, proficiency in Parlog++ 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 Parlog++.

What does this simple Parlog++ code do?
PROC hello_world IS
  OUTPUT ('Hello, world!')
ENDPROC
This code prints 'Hello, world!' to the standard output.
What does this Parlog++ code do?
PROC add(X, Y, Z) IS
  Z = X + Y
ENDPROC
This code defines a procedure 'add' that takes three arguments X, Y, and Z. It adds X and Y and assigns the result to Z.
What will be the output of this Parlog++ code that manipulates an array?
PROC sum_array(Array, Sum) IS
  Sum = 0
  FOR I IN 1..Array.length DO
    Sum = Sum + Array[I]
  ENDFOR
ENDPROC
This code defines a procedure 'sum_array' that takes an array and a variable 'Sum'. It calculates the sum of all elements in the array and assigns the result to 'Sum'.
What does this Parlog++ code do related to threading?
PROC parallel_sum(X, Y, Z) IS
  PAR
    Z1 = X + Y
  AND
    Z2 = Y + X
  END PAR
  Z = Z1 + Z2
ENDPROC
This code defines a procedure 'parallel_sum' that takes three arguments X, Y, and Z. It calculates the sum of X and Y in parallel twice and assigns the sum of these two results to Z.

Wrap-up questions

Final candidate for Parlog++ 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 Parlog++ application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What are the limitations of Parlog++?

Limitations of Parlog++ include the lack of built-in support for exception handling, the complexity of its syntax and semantics, and the difficulty of optimizing programs for performance.

Describe the difference between 'strong' and 'weak' fairness in Parlog++.

Strong fairness in Parlog++ means that every process that is continuously enabled will eventually be executed. Weak fairness, on the other hand, only guarantees that a process will be executed if it remains enabled for an infinite amount of time.

How would you debug a complex Parlog++ program?

Debugging a complex Parlog++ program can involve techniques such as tracing the execution of the program, analyzing the state of the processes and channels, and using formal methods to verify the correctness of the program.

Parlog++ application related

Product Perfect's Parlog++ development capabilities

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

Parlog++ Consultive assessments

Parlog++ Application Conversion Assessment Parlog++ Application Integration Assessment Parlog++ Data & Database Integration Assessment

Custom Parlog++ development projects

Custom Parlog++ App Conversion Parlog++ Custom App Development Process App UI Design for Parlog++ Facelifts

Hiring guide for Parlog++ Engineers

Parlog++ Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

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

Parlog++ Consultive assessments

Custom Parlog++ development projects