Picat Using Standard Modules Questions and Answers

Question 1

A developer needs to get a list of all files and directories in the current working directory. Which predicate from the `os` module should be used for this purpose?

Accepted Answer

os:listdir(".", List)

Answer

The `os:listdir(Path, List)` predicate is used to retrieve the names of entries in a directory. `Path` is the directory to scan, and `List` will be bound to a list of strings representing the files and subdirectories. Using `.` for the path refers to the current directory.

Question 2

When processing a list of numerical data, you need to find the sum of all elements. Which function from the `math` module accomplishes this?

Accepted Answer

math:sum/1

Answer

The `math:sum/1` function takes a list of numbers as an argument and returns their sum. It is the standard function for this common mathematical operation.

Question 3

A Picat script needs to be executed from the command line with several arguments. How can the script access these arguments?

Accepted Answer

By calling `sys:get_args()`

Answer

The `sys` module provides interaction with the Picat system environment. The `sys:get_args()` function returns a list of strings, where each string is a command-line argument passed to the script. [21, 24]

Question 4

You need to combine two lists, `L1` and `L2`, into a single list of pairs, where each pair contains one element from `L1` and one from `L2` at the corresponding position. Which predicate from the `util` module is designed for this?

Accepted Answer

util:zip(L1, L2, Pairs)

Answer

The `util:zip/3` predicate is the standard way to combine two lists into a list of pairs. For example, `zip([a,b], [1,2], Z)` will result in `Z = [{a,1}, {b,2}]`. The name comes from the analogy of a zipper interlocking two sides.

Question 5

A developer needs to read the entire content of a text file named `config.txt` into a single string. Which function from the `io` module should be used?

Accepted Answer

io:read_file_to_string("config.txt")

Answer

The `io:read_file_to_string/1` function is specifically designed to open, read the entire contents of a file, and return those contents as a single string, closing the file automatically.

Picat Practice Test

Picat Practice Test

Picat Using Standard Modules Questions and Answers