SXML Parser and Pretty Printer

Overview: A simple XML-like language parser (SXML) and a corresponding pretty printer. The SXML data type represents the structured XML-like content, and the code includes parsers for elements, attributes, and text content. The pretty printer formats the parsed SXML back into a readable and formatted XML-like representation.

Module Structure:

• SXML module exports SXML, sxmlP, sxmlD, and main.
• SXML type represents the parsed SXML content.
• sxmlP is the parser for SXML content.
• sxmlD is the pretty printer for SXML content.
• main is the entry point for the program, reading input from the command line, parsing it, and pretty printing the result.

Functionality:

• Parsing: The code provides parsers for elements (eltP), attributes (attP), and text content (textP).

• Pretty Printing: The code defines functions (sxmlD, eltD, tagD, attD, itemsD, itemD) to format parsed SXML content into a readable representation.

• The code includes utility functions (valid, validName, validAttValue, validText) to validate different components of SXML.

• The getArgs function is used to read command line arguments, and the getContents function reads input from standard input.

• The project uses various Haskell modules, including Control.Monad, System.Environment, Text.Read, and custom parser modules (Parser and PrettyPrinter).