feat: basic structure of the language done

.env.example

@@ -1,3 +1,61 @@
-PRINT_COMMAND="Your Print Command!"
-VARIABLE_DECLARE="Your Variable declaration Command!"
+PRINT_COMMAND=print
+VARIABLE_DECLARE=var
 
+# Customizable keyword mappings
+KEYWORD_PRINT=show
+KEYWORD_IF=when
+KEYWORD_ELSE=otherwise
+KEYWORD_WHILE=repeat
+KEYWORD_FOR=loop
+KEYWORD_FUNCTION=def
+KEYWORD_RETURN=give
+KEYWORD_BREAK=stop
+KEYWORD_CONTINUE=skip
+KEYWORD_AND=also
+KEYWORD_OR=either
+KEYWORD_NOT=negate
+KEYWORD_TRUE=yes
+KEYWORD_FALSE=no
+KEYWORD_NONE=nothing
+KEYWORD_VAR=let
+
+# Custom Error Messages
+# You can override any error message by uncommenting and modifying these lines
+
+# Syntax Errors
+#ERROR_SYNTAX_GENERIC="🦆 Oops! Your code has a syntax error at line {line}"
+#ERROR_MISSING_BRACKET="🦆 Missing a {bracket_type} at line {line}. Every duck needs its pair!"
+#ERROR_INVALID_TOKEN="🦆 Found an unexpected {token} at line {line}. That's not duck-friendly!"
+#ERROR_UNEXPECTED_TOKEN="🦆 Found a {token} where it shouldn't be at line {line}. Ducks like order!"
+#ERROR_INVALID_INDENTATION="🦆 Your code's indentation at line {line} is making ducks dizzy!"
+
+# Runtime Errors
+#ERROR_DIVISION_BY_ZERO="🦆 Even ducks know you can't divide by zero!"
+#ERROR_UNDEFINED_VAR="🦆 Can't find the variable '{var_name}'. Did it fly away?"
+#ERROR_TYPE_MISMATCH="🦆 Expected a {expected_type} but got a {actual_type}. Ducks of a feather..."
+#ERROR_INDEX_OUT_OF_RANGE="🦆 Index {index} is out of the pond! Maximum is {max_index}"
+#ERROR_STACK_OVERFLOW="🦆 Too many nested ducks! They're starting to pile up!"
+
+# Function Errors
+#ERROR_UNDEFINED_FUNCTION="🦆 The function '{func_name}' is MIA (Missing In Action)!"
+#ERROR_INVALID_ARGUMENTS="🦆 Expected {expected} ducks, but got {actual}. Count them again!"
+#ERROR_RECURSION_LIMIT="🦆 Your ducks are going in circles! Time to break the loop"
+
+# Type Errors
+#ERROR_TYPE_CONVERSION="🦆 Can't transform a {from_type} into a {to_type}. Magic has limits!"
+#ERROR_INVALID_OPERATION="🦆 Can't {operation} with {type1} and {type2}. They don't mix!"
+#ERROR_NULL_REFERENCE="🦆 Found an empty nest where a value should be!"
+
+# IO Errors
+#ERROR_FILE_NOT_FOUND="🦆 The file '{file}' is playing hide and seek... and winning!"
+#ERROR_PERMISSION_DENIED="🦆 No access to '{file}'. This pond is private!"
+#ERROR_IO_ERROR="🦆 Duck communication error: {details}"
+
+# Configuration
+#ERROR_INVALID_KEYWORD="🦆 The keyword '{keyword}' isn't in the duck dictionary!"
+#ERROR_DUPLICATE_KEYWORD="🦆 '{keyword}' is already used for {existing_use}. Ducks need unique names!"
+#ERROR_INVALID_CONFIG="🦆 Your duck configuration is invalid: {details}"
+
+# Import/Module
+#ERROR_MODULE_NOT_FOUND="🦆 Can't find the module '{module}'. Is it hiding?"
+#ERROR_CIRCULAR_IMPORT="🦆 Your imports are going in circles! Ducks are getting dizzy!"

custom_program.duck

@@ -0,0 +1,47 @@
+# Function definition using 'def' instead of 'function'
+def factorial(n) {
+    # Using 'when' instead of 'if'
+    when n < 0 {
+        give 0
+    }
+
+    when n <= 1 {
+        give 1
+    }
+
+    let result = 1
+    let counter = n
+
+    # Using 'repeat' instead of 'while'
+    repeat counter > 1 {
+        result = result * counter
+        counter = counter - 1
+    }
+
+    give result
+}
+
+# Using 'let' instead of 'var'
+let numbers = [1, 2, 3, 4, 5]
+
+# Using 'show' instead of 'print'
+show "Testing custom keywords!"
+
+# Using 'when/otherwise' instead of 'if/else'
+when 5 > 3 {
+    show "5 is greater than 3"
+} otherwise {
+    show "This won't be shown"
+}
+
+# Test logical operators
+let x = yes  # Using 'yes' instead of 'true'
+let y = no   # Using 'no' instead of 'false'
+
+when x also negate y {  # Using 'also' instead of 'and', 'negate' instead of 'not'
+    show "Logic works!"
+}
+
+show "Factorial of 5 is:"
+let result = factorial(5)
+show result