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Limbo is a programming language developed in the late 1990s for the Inferno operating system by Bell Labs, the same research group responsible for creating Unix and C. It was designed to be a safer, more modern alternative to C, with features like garbage collection and strong type checking. Limbo is primarily used for distributed systems and is known for its simplicity and portability. Its syntax is similar to that of C, but it also incorporates elements from other languages such as Pascal and Alef. References for this information can be found in "The Inferno Operating System" by Dennis Ritchie and "The Limbo Programming Language" by Vita Nuova.

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

First 20 minutes

General Limbo app knowledge and experience

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

What is the primary use of Limbo?

Limbo is primarily used for systems programming, as well as for applications that require distributed systems.

How would you compile a Limbo program?

To compile a Limbo program, you would use the Limbo compiler, 'limbo', followed by the name of the .b file.

What are the key features of Limbo programming language?

Key features of Limbo include strong typing, garbage collection, simple syntax, and support for distributed computing.

Describe the difference between Limbo and C programming languages.

While both are used for systems programming, Limbo is more modern and includes features like garbage collection and support for distributed computing. C, on the other hand, is older and does not include these features.

How would you handle errors in Limbo?

In Limbo, errors are handled using exception handling constructs like 'raise', 'if' and 'rescue'.

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What you’re looking for early on

Does the candidate demonstrate a strong understanding of Limbo programming language?

Has the candidate worked on projects using Limbo in the past?

Is the candidate able to problem solve and debug in Limbo?

Can the candidate communicate effectively about their process and solutions?

Next 20 minutes

Specific Limbo 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.

What is the purpose of the 'load' module in Limbo?

The 'load' module in Limbo is used to dynamically load modules at runtime.

Describe the difference between 'ref' and 'adts' in Limbo.

'Ref' is used to create reference types, while 'adts' are abstract data types. The main difference is that 'ref' types are mutable, while 'adts' are not.

How would you implement concurrency in Limbo?

Concurrency in Limbo is implemented using 'spawn' to create new threads of execution.

What are the data types available in Limbo?

Limbo supports several data types, including int, real, byte, big, string, list, array, and tuple.

Describe the difference between 'include' and 'import' in Limbo.

'Include' is used to include the contents of another file, while 'import' is used to import a module.

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

What does this simple Limbo code do?
implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
sys->print("Hello, World!\n");
}
This is a simple Limbo program that prints 'Hello, World!' to the console. It includes the 'sys.m' module, loads the Sys module, and uses the 'print' function from the Sys module to print the string.
What will be the output of this Limbo code?
implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
for(i := 0; i < 5; i++)
sys->print("%d\n", i);
}
This Limbo program will print the numbers 0 through 4, each on a new line. It uses a for loop to iterate from 0 to 4 and the 'print' function from the Sys module to print each number.
What does this Limbo code do with an array?
implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
arr := array of int(5);
for(i := 0; i < len arr; i++)
arr[i] = i * i;
for(i := 0; i < len arr; i++)
sys->print("%d\n", arr[i]);
}
This Limbo program creates an array of integers with 5 elements, assigns each element the square of its index, and then prints each element. It uses two for loops, one to assign the values and one to print them.
What does this Limbo code do with threads?
implement Main;
include "sys.m";
sys: Sys;

init(nil: ref Draw->Context, nil: list of string)
{
sys = load Sys Sys->PATH;
thread PrintHello()
{
sys->print("Hello from thread!\n");
}
}
This Limbo program creates a new thread that prints 'Hello from thread!' to the console. It uses the 'thread' keyword to create the new thread and the 'print' function from the Sys module to print the string.

Wrap-up questions

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

How would you implement a distributed system in Limbo?

A distributed system in Limbo can be implemented using the 'Net' module, which provides functions for network communication.

What is the purpose of the 'sys' module in Limbo?

The 'sys' module in Limbo provides functions for system-level operations, such as file I/O and process management.

Describe the difference between 'self' and 'this' in Limbo.

'Self' refers to the current instance of a module, while 'this' refers to the current instance of an object.

Limbo application related

Product Perfect's Limbo development capabilities

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

Limbo Consultive assessments

Limbo Application Conversion Assessment Limbo Application Integration Assessment Limbo Data & Database Integration Assessment

Custom Limbo development projects

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

Hiring guide for Limbo Engineers

Limbo Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

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

Limbo Consultive assessments

Custom Limbo development projects