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

Befunge is a stack-based, reflective, esoteric programming language developed by Chris Pressey in 1993. It is unique for its two-dimensional toroidal grid structure, which allows the control flow to move in four directions: left, right, up and down. The language was designed as a challenge to traditional compiler theory and features self-modifying code. Befunge's unusual approach has made it popular for programming contests and academic study of unconventional computing models. Its original implementation and subsequent versions are available on the author's website and GitHub repository.

First 20 minutes

General Befunge knowledge and experience

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

What are the uses of the 'p' and 'g' commands in Befunge?

'p' and 'g' commands are used for self-modifying code. 'p' puts a value onto the playfield, while 'g' gets a value from the playfield.

How would you handle errors in Befunge?

Handling errors in Befunge is tricky due to its esoteric nature. However, one can use the 'g' instruction to get a value from the playfield and check if it's expected before proceeding.

Describe the difference between Befunge-93 and Befunge-98.

Befunge-93 is the original version with a fixed playfield size of 80x25 and only one stack. Befunge-98 is an extension with multiple stacks, self-modifying code, and a playfield of arbitrary size.

What are the core principles of Befunge programming language?

Befunge is a two-dimensional, stack-based, reflective esolang. It's designed to be as difficult to compile as possible. The core principles include multidimensionality, unpredictability, and interactivity.

How would you explain the concept of stack in Befunge?

In Befunge, a stack is a data structure that follows the Last-In-First-Out (LIFO) principle. It's used to store and retrieve data, where the most recently stored data is the first to be retrieved.

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What youre looking for early-on

Does the candidate show enthusiasm for the role?

A passionate candidate is more likely to be motivated and committed to the job.

Has the candidate worked on any projects or tasks using Befunge?

Experience with real-world projects can demonstrate the candidate's ability to apply their skills effectively.

Does the candidate show an ability to learn and adapt?

Technology is always evolving, and a good developer should be able to keep up with new trends and tools.

Is the candidate able to explain their thought process clearly?

This indicates good communication skills, which are important for teamwork and for explaining complex concepts to non-technical stakeholders.

Can the candidate demonstrate problem-solving skills?

Befunge is a complex language, and the ability to solve problems is crucial for a developer.

Does the candidate have a strong understanding of Befunge?

The candidate should have a deep knowledge of Befunge, as it is the primary skill required for the position.

Next 20 minutes

Specific Befunge development questions

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

Describe the difference between ':', ';', and '$' commands in Befunge.

':' duplicates the top stack value, ';' starts and ends a comment, and '$' pops and discards the top stack value.

How would you debug a Befunge program?

Debugging Befunge is challenging due to its esoteric nature. However, one can use the '?' command to randomly change the direction of the instruction pointer for testing purposes.

What are the uses of '_' and '|' commands in Befunge?

'_' and '|' are conditional commands. '_' pops a value and moves right if it's zero, left otherwise. '|' pops a value and moves down if it's zero, up otherwise.

How would you implement a loop in Befunge?

Loops in Befunge are created using the '<', '>', '^', and 'v' commands to direct the instruction pointer, along with conditional statements like '_' and '|'.

Describe the difference between '@' and '#' commands in Befunge.

'@' command ends the program while '#' command is a bridge that makes the instruction pointer skip the next cell.

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A skilled Befunge engineer should demonstrate proficiency in stack-based, multi-dimensional questions, problem-solving abilities, and creativity in code writing. Red flags include inability to explain their thought process or code logic, lack of experience with esoteric questions and difficulty in debugging.

Digging deeper

Code questions

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

What does this simple Befunge code do?`>00g1-:!v
 ^  <  @
This is a simple Befunge code for a decrementing counter. It gets the value at position (0,0), subtracts 1 from it, and puts it back. If the result is not zero, it loops back and repeats the process. If the result is zero, it ends the program.
What does this Befunge code do that includes a '#' character?`>1#v
 ^  <  @
This Befunge code, with the '#' character, is a simple example of a bridge. The '#' character in Befunge is a bridge, which causes the instruction pointer to skip the next cell in the current direction of the instruction pointer. In this case, it skips over the 'v' character and continues executing to the right.
What will be the output of this Befunge code that manipulates a stack?`>12345$@
This Befunge code pushes the numbers 1, 2, 3, 4, 5 onto the stack, then the '$' command pops and discards the top value from the stack, and finally, the '@' command ends the program. So, the final state of the stack will be [1, 2, 3, 4].
What does this Befunge code do that uses the 'p' and 'g' commands?`>00p1+00g.@
This Befunge code demonstrates the use of the 'p' and 'g' commands, which are used for storing and retrieving values in the playfield. The 'p' command pops y, x, and v, then changes the character at (x,y) to the character with ASCII value v. The 'g' command pops y and x, then pushes the ASCII value of the character at that position. In this case, the code stores 1 at position (0,0) and retrieves it immediately, then outputs it.
What does this Befunge code do that involves a loop?`>1+:3g`-!v
 ^  <  @
This Befunge code is a loop that increments a counter, retrieves a value from the playfield, subtracts the counter from it, and checks if the result is zero. If the result is not zero, it loops back and repeats the process. If the result is zero, it ends the program.
What does this advanced Befunge code do?`>"Hello, World!"v
v:,_@>
      >  ^
This advanced Befunge code is a 'Hello, World!' program. It pushes the ASCII values of the characters of 'Hello, World!' onto the stack, then enters a loop that pops and outputs each character. When it encounters a zero (the end of the string), it ends the program.

Wrap-up questions

Final candidate for Befunge role questions

The final few interview questions for a Befunge candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.

What are the challenges of writing efficient code in Befunge and how would you overcome them?

Challenges include its two-dimensional nature, unpredictability, and lack of traditional control structures. Overcoming these requires a deep understanding of the language, creative problem-solving, and careful planning of the instruction pointer's path.

How would you create a function in Befunge?

Befunge doesn't have functions in the traditional sense. However, you can create a 'function-like' behavior by isolating a piece of code and using the instruction pointer movement commands to call and return from it.

Describe the difference between '0'-'9' and 'a'-'f' commands in Befunge.

'0'-'9' push corresponding decimal numbers onto the stack, while 'a'-'f' push hexadecimal values from 10 to 15.

What are the uses of '!', '`', and '~' commands in Befunge?

'!' is a logical NOT, '`' is a greater-than comparison, and '~' reads a character from input.

How would you implement recursion in Befunge?

Recursion in Befunge can be implemented using the 'r' command, which reflects the instruction pointer, effectively creating a loop until a base case is met.

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Befunge application related

Product Perfect's Befunge development capabilities

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

Befunge Consultive assessments

Befunge Application Conversion Assessment Befunge Application Integration Assessment Befunge Data & Database Integration Assessment

Custom Befunge development projects

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

Befunge Developer Hiring Guide

Hiring Guide for Befunge Engineers

First 20 minutes

General Befunge knowledge and experience

What are the uses of the 'p' and 'g' commands in Befunge?

How would you handle errors in Befunge?

Describe the difference between Befunge-93 and Befunge-98.

What are the core principles of Befunge programming language?

How would you explain the concept of stack in Befunge?

What youre looking for early-on

Does the candidate show enthusiasm for the role?

Has the candidate worked on any projects or tasks using Befunge?

Does the candidate show an ability to learn and adapt?

Is the candidate able to explain their thought process clearly?

Can the candidate demonstrate problem-solving skills?

Does the candidate have a strong understanding of Befunge?

Next 20 minutes

Specific Befunge development questions

Describe the difference between ':', ';', and '$' commands in Befunge.

How would you debug a Befunge program?

What are the uses of '_' and '|' commands in Befunge?

How would you implement a loop in Befunge?

Describe the difference between '@' and '#' commands in Befunge.

The ideal back-end app developer

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

What does this simple Befunge code do?

This is a simple Befunge code for a decrementing counter. It gets the value at position (0,0), subtracts 1 from it, and puts it back. If the result is not zero, it loops back and repeats the process. If the result is zero, it ends the program.

What does this Befunge code do that includes a '#' character?

What will be the output of this Befunge code that manipulates a stack?

This Befunge code pushes the numbers 1, 2, 3, 4, 5 onto the stack, then the '$' command pops and discards the top value from the stack, and finally, the '@' command ends the program. So, the final state of the stack will be [1, 2, 3, 4].

What does this Befunge code do that uses the 'p' and 'g' commands?

What does this Befunge code do that involves a loop?

This Befunge code is a loop that increments a counter, retrieves a value from the playfield, subtracts the counter from it, and checks if the result is zero. If the result is not zero, it loops back and repeats the process. If the result is zero, it ends the program.

What does this advanced Befunge code do?

This advanced Befunge code is a 'Hello, World!' program. It pushes the ASCII values of the characters of 'Hello, World!' onto the stack, then enters a loop that pops and outputs each character. When it encounters a zero (the end of the string), it ends the program.

Wrap-up questions

Final candidate for Befunge role questions

What are the challenges of writing efficient code in Befunge and how would you overcome them?

How would you create a function in Befunge?

Describe the difference between '0'-'9' and 'a'-'f' commands in Befunge.

What are the uses of '!', '`', and '~' commands in Befunge?

How would you implement recursion in Befunge?

Befunge Consultive assessments

Custom Befunge development projects