Intro: Safe and minimal Haskell Prelude

Intro is a modern Prelude which provides safe alternatives for most of the partial functions and follows other best practices, e.g., Text is preferred over String. For String overloading the extension 'OverloadedStrings' should be used. Container types and Monad transformers are provided.

Most important - this Prelude tries to keep things simple and minimal. This means it just reexports from base and commonly used libraries and adds only very few additional functions.

List of design decisions:

• Keep everything at one place (Actually there are three modules; Intro.Trustworthy is needed for Safe Haskell)
• Conservative extension over the base Prelude
• Rely only on common additional libraries
• Avoid writing custom functions
• Export everything explicitly to provide a stable interface and good documentation
• Export only total functions or provide safe alternatives (Very few exceptions like div etc.)
• Prefer Text over String, provide ConvertString and EncodeString
• Provide monad transformers
• Provide container types
• Prefer generic functions
• Debugging functions, like 'Intro.Trustworthy.trace' and 'undefined' are available but produce compile time warnings
• Replace error with panic
• Compatibility with unqualified import of Control.Lens and Optics