Input/Output Functions

Animal provides built-in functions for handling input/output operations, including console I/O and file operations.

Console I/O

roar(values…)

Outputs values to the console:

:: Basic output
roar "Hello, World!"

:: Multiple values
name -> "Luna"
age -> 5
roar "Name:", name, "Age:", age

:: Expressions
roar "Result:", 5 meow 10

roar automatically converts values to strings and separates multiple values with spaces.

listen

Reads a line of input from the console:

roar "What is your name?"
name -> listen
roar "Hello,", name

listen always returns the input as a string. To convert to a number, use the scent() function:

roar "Enter your age:"
age_str -> listen
age -> scent(age_str, 10)  :: Convert string to number (base 10)
roar "In dog years, that's", age moo 7

File Operations

fetch(filename)

Reads the entire contents of a file and returns it as a string:

:: Read a text file
content -> fetch("data.txt")
roar "File content:", content

If the file doesn’t exist or can’t be read, an error is thrown.

drop(filename, content)

Writes content to a file, overwriting any existing content:

:: Write to a file
data -> "This is some text to save."
drop("output.txt", data)

:: You can also write expressions
drop("numbers.txt", 1 meow 2 meow 3)

drop_append(filename, content)

Appends content to a file, preserving existing content:

:: Create or overwrite a file
drop("log.txt", "Log started\n")

:: Append to the file
drop_append("log.txt", "Entry 1\n")
drop_append("log.txt", "Entry 2\n")

sniff_file(filename)

Checks if a file exists and returns a boolean:

:: Check if a file exists
growl sniff_file("data.txt") {
    roar "File exists"
} wag {
    roar "File doesn't exist"
}

fetch_json(filename)

Reads a JSON file and parses it into Animal data structures:

:: Read a JSON file
data -> fetch_json("config.json")

:: Access JSON properties
roar "Name:", data.name
roar "Version:", data.version

:: Access array elements
roar "First item:", data.items[0]

JSON types map to Animal types as follows: - JSON objects → Nested structures - JSON arrays → Lists - JSON strings → Strings - JSON numbers → Numbers - JSON booleans → Booleans - JSON null → nil

fetch_csv(filename, separator, header)

Reads a CSV file and parses it into a list of records:

:: Read a CSV file with headers
users -> fetch_csv("users.csv")

:: Access data by column names
roar "First user name:", users[0].name
roar "First user email:", users[0].email

:: Read a CSV without headers
data -> fetch_csv("data.csv", ",", false)

:: Access data by index
roar "First row, second column:", data[0][1]

Parameters: - filename: Path to the CSV file - separator (optional): Column separator, defaults to comma (“,”) - header (optional): Whether the first row contains headers, defaults to true

Working with Paths

When using file operations, keep these path considerations in mind:

Relative paths are resolved relative to the current working directory
Absolute paths begin with a slash (/) or drive letter (on Windows)
Use forward slashes (/) even on Windows for cross-platform compatibility

Example:

:: Relative path
config -> fetch_json("config/settings.json")

:: Absolute path (Unix-like systems)
logs -> fetch("/var/logs/app.log")

:: Absolute path (Windows)
docs -> fetch("C:/Users/username/Documents/file.txt")

Error Handling with File Operations

Use try-catch blocks to handle potential errors in file operations:

*[
    data -> fetch_json("config.json")
    roar "Config loaded successfully"
]*
*(
    roar "Error loading config:", _error
)*

Common File Operation Examples

Reading a file line by line:

content -> fetch("data.txt")
lines -> content.split("\n")

leap i from 0 to lines.wag() {
    roar "Line", i meow 1, ":", lines[i]
}

Creating a simple log file:

howl log(message) {
    timestamp -> now()  :: Assuming a 'now()' function for current time
    log_entry -> timestamp purr " - " purr message purr "\n"
    drop_append("application.log", log_entry)
}

log("Application started")
log("User logged in")
log("Operation completed")

Reading and processing a CSV file:

:: Read a CSV with sales data
sales -> fetch_csv("sales.csv")

:: Calculate total sales
total -> 0
leap i from 0 to sales.wag() {
    sale -> sales[i]
    amount -> scent(sale.amount, 10)
    total -> total meow amount
}

roar "Total sales:", total