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DAML+++ is a computer programming language developed by the Defense Advanced Research Projects Agency (DARPA) in the United States. It was designed as an extension of the DAML language, specifically for applications in web ontology and semantic web services. The "+++" signifies enhancements made to the original DAML language, including improved expressivity and reasoning capabilities. The development of DAML+++ was part of DARPA's Agent Markup Language program, aimed at creating software agents that can understand and use web content. This information is sourced from DARPA's official documentation and various scholarly articles on semantic web technologies.

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

First 20 minutes

General DAML+++ app knowledge and experience

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

How would you describe DAML+++ in your own words?

DAML+++ is an extension of DAML, which is a powerful language for modeling and executing multi-party agreements. DAML+++ includes additional features that enhance the capabilities of DAML, allowing for more complex and flexible smart contract development.

What are some key features of DAML+++ that differentiate it from DAML?

DAML+++ has additional features that are not present in DAML, such as advanced privacy features, more robust error handling, and improved support for asynchronous programming.

Describe the difference between DAML and DAML+++ in terms of privacy features.

While DAML already has strong privacy features, DAML+++ takes this a step further by introducing advanced privacy controls, allowing developers to specify more granular permissions and restrictions on data access.

How would you handle errors in DAML+++?

DAML+++ provides robust error handling mechanisms. I would use the `catch` and `try` constructs to handle exceptions and prevent the program from crashing unexpectedly.

What is the role of the 'submit' function in DAML+++?

The 'submit' function in DAML+++ is used to send commands or transactions to the ledger. It plays a crucial role in the interaction between the smart contract and the ledger.

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What you’re looking for early on

Does the candidate have a strong understanding of DAML+++ and its applications?

Has the candidate demonstrated problem-solving skills during the interview?

Is the candidate able to communicate effectively?

Does the candidate show a willingness to learn and adapt?

Next 20 minutes

Specific DAML+++ 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.

How would you use the 'exercise' function in DAML+++?

The 'exercise' function in DAML+++ is used to trigger a choice on a contract. I would use it by passing the contract ID and the choice arguments.

What are some of the asynchronous programming features in DAML+++?

DAML+++ supports asynchronous programming features such as futures and promises. These features allow for non-blocking operations, which can greatly improve the efficiency of the program.

Describe how you would implement a multi-party agreement using DAML+++.

To implement a multi-party agreement in DAML+++, I would first define the parties involved and their respective roles. Then, I would use the 'template' keyword to define the agreement, specifying the rights and obligations of each party. Finally, I would use the 'choice' keyword to define the possible actions that each party can take.

How would you test a smart contract written in DAML+++?

To test a smart contract written in DAML+++, I would use the DAML Script and DAML Test toolkits. These provide a way to write and run automated tests for DAML code, ensuring that the smart contract behaves as expected.

What is the purpose of the 'with' keyword in DAML+++?

The 'with' keyword in DAML+++ is used in the definition of choices. It allows you to specify the parameters that the choice takes.

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

What does this simple DAML script do?
template HelloWorld
  with
    sender: Party
  where
    signatory sender
    controller sender can
      HelloWorld: ()
This is a basic DAML contract template named 'HelloWorld'. It has one signatory and one controller, both of which are the 'sender'. The 'HelloWorld' choice allows the 'sender' to create an instance of this contract.
What does the following DAML code snippet do?
template T
  with
    p: Party
  where
    signatory p
    controller p can
      CreateAnotherT: ContractId T
        do
          create this
This DAML code defines a contract template 'T' with a party 'p' as the signatory. It has a choice 'CreateAnotherT' that allows the party 'p' to create another contract of the same type 'T'.
What will be the output of the following DAML code snippet?
let xs = [1, 2, 3, 4, 5]
let ys = map (+1) xs
This DAML code first defines a list 'xs' of integers. Then it applies the function '(+1)' to each element of 'xs' using the 'map' function, resulting in a new list 'ys'. The output will be the list '[2, 3, 4, 5, 6]'.
What does the following DAML code snippet do?
template T
  with
    p: Party
  where
    signatory p
    nonconsuming choice DoSomething: ()
      controller p
      do
        return ()
This DAML code defines a contract template 'T' with a party 'p' as the signatory. It has a non-consuming choice 'DoSomething' that allows the party 'p' to execute some action without archiving the contract.

Wrap-up questions

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

How would you handle concurrency issues in DAML+++?

In DAML+++, concurrency issues can be handled by using the 'submitMustFail' function. This function allows you to specify a condition under which a transaction should fail, helping to prevent concurrency-related errors.

Describe the difference between 'signatory' and 'observer' in DAML+++.

In DAML+++, 'signatory' refers to the parties that authorize the creation of a contract, while 'observer' refers to the parties that have visibility of the contract but do not have the authority to authorize it.

How would you use the 'map' function in DAML+++?

The 'map' function in DAML+++ is used to apply a function to each element of a list. I would use it by passing the function and the list as arguments.

DAML+++ application related

Product Perfect's DAML+++ development capabilities

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

DAML+++ Consultive assessments

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

Custom DAML+++ development projects

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

Hiring guide for DAML+++ Engineers

DAML+++ Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

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

DAML+++ Consultive assessments

Custom DAML+++ development projects