Function gen: A Journey into Recursive Programming

1. What is the output of the function call gen (4)?

2. What is the return value for a given value n, in general?

3. (Extra 5 points) The function definition is not tail recursive. Convert it into tail recursion.

1. The output of the function call gen (4) is `[aaaa,aaab,aaba,aabb,abaa,abab,abba,abbb,baaa,baab,baba,babb,bbba,bbbb]`.

2. The return value for a given value n in general is a list of binary strings of length n.

3. The function definition for gen in Haskell is not tail recursive. To convert it into a tail recursive function, you need to use an accumulator to store the result.

The function gen involves recursive programming in the languages of Picat and Haskell. It generates binary strings based on certain conditions and constraints.

Output of gen (4):

When the function gen is called with the argument 4, it generates a list of binary strings of length 4 as output. These strings are combinations of 'a' and 'b' characters, following the conditions defined in the function.

Return value for a given value n:

For any given value n, the return value of the gen function is a list of binary strings of length n. These strings are constructed recursively based on the rules specified in the function definition.

Converting to tail recursion:

The function definition for gen in Haskell is not tail recursive, which can lead to stack overflow for large inputs. To make it tail recursive, we need to refactor the code using an accumulator to store partial results and optimize memory usage.