rewritten introduction

Doc/lib/libintro.tex

 \chapter{Introduction}
 
-The Python library consists of three parts, with different levels of
-integration with the interpreter.
-Closest to the interpreter are built-in types, exceptions and functions.
-Next are built-in modules, which are written in \C{} and linked statically
-with the interpreter.
-Finally there are standard modules that are implemented entirely in
-Python, but are always available.
-For efficiency, some standard modules may become built-in modules in
-future versions of the interpreter.
-\indexii{built-in}{types}
-\indexii{built-in}{exceptions}
-\indexii{built-in}{functions}
-\indexii{built-in}{modules}
-\indexii{standard}{modules}
-\indexii{\C{}}{language}
+The ``Python library'' contains several different kinds of components.
+
+It contains data types that would normally be considered part of the
+``core'' of the language, such as numbers and lists.  For these types,
+the core language defines the form of literals and places some
+constraints on their semantics, but it does not fully describe the
+semantics.  (On the other hand, the core of the language defines
+syntactic properties like the spelling and priorities of operators.)
+
+The library also contains built-in functions and exceptions ---
+objects that can be used by all Python code without the need of an
+\code{import} statement.  Some of these are defined by the core
+language, but many are not essential for the core semantics and are
+only described here.
+
+The bulk of the library, however, consists of a collection of modules.
+There are many ways to dissect this collection.  Some modules are
+written in C and built in to the Python interpreter; others are
+written in Python and imported in source form.  Some modules provide
+interfaces that are highly specific to Python, like printing a stack
+trace; some provide interfaces that are specific to particular
+operating systems, like socket I/O; others provide interfaces that are
+specific to a particular application domain, like the World-Wide Web.
+Some modules are avaiable in all versions and ports of Python; others
+are only available when the underlying system supports or requires
+them; yet others are available only when a particular configuration
+option was chosen at the time when Python was compiled and installed.
+
+This manual is organized ``from the inside out'': it first describes
+the built-in data types, then the built-in functions and exceptions,
+and finally the modules, grouped in chapters of related modules.  The
+ordering of the chapters as well as the ordering of the modules within
+each chapter is roughly from most relevant to least important.
+
+This means that if you start reading this manual from the start, and
+skip to the next chapter when you get bored, you will get a reasonable
+overview of the available modules and application areas that are
+supported by the Python library.  Of course, you don't \emph{have} to
+read it like a novel --- you can also browse the table of contents (in
+front of the manual) or look for a specific function, module or term
+in the index (in the back).  And finally, if you enjoy learning about
+random subjects, you choose a random page number (see module
+\code{rand}) and read a section or two.
+
+Let the show begin!

Doc/libintro.tex

 \chapter{Introduction}
 
-The Python library consists of three parts, with different levels of
-integration with the interpreter.
-Closest to the interpreter are built-in types, exceptions and functions.
-Next are built-in modules, which are written in \C{} and linked statically
-with the interpreter.
-Finally there are standard modules that are implemented entirely in
-Python, but are always available.
-For efficiency, some standard modules may become built-in modules in
-future versions of the interpreter.
-\indexii{built-in}{types}
-\indexii{built-in}{exceptions}
-\indexii{built-in}{functions}
-\indexii{built-in}{modules}
-\indexii{standard}{modules}
-\indexii{\C{}}{language}
+The ``Python library'' contains several different kinds of components.
+
+It contains data types that would normally be considered part of the
+``core'' of the language, such as numbers and lists.  For these types,
+the core language defines the form of literals and places some
+constraints on their semantics, but it does not fully describe the
+semantics.  (On the other hand, the core of the language defines
+syntactic properties like the spelling and priorities of operators.)
+
+The library also contains built-in functions and exceptions ---
+objects that can be used by all Python code without the need of an
+\code{import} statement.  Some of these are defined by the core
+language, but many are not essential for the core semantics and are
+only described here.
+
+The bulk of the library, however, consists of a collection of modules.
+There are many ways to dissect this collection.  Some modules are
+written in C and built in to the Python interpreter; others are
+written in Python and imported in source form.  Some modules provide
+interfaces that are highly specific to Python, like printing a stack
+trace; some provide interfaces that are specific to particular
+operating systems, like socket I/O; others provide interfaces that are
+specific to a particular application domain, like the World-Wide Web.
+Some modules are avaiable in all versions and ports of Python; others
+are only available when the underlying system supports or requires
+them; yet others are available only when a particular configuration
+option was chosen at the time when Python was compiled and installed.
+
+This manual is organized ``from the inside out'': it first describes
+the built-in data types, then the built-in functions and exceptions,
+and finally the modules, grouped in chapters of related modules.  The
+ordering of the chapters as well as the ordering of the modules within
+each chapter is roughly from most relevant to least important.
+
+This means that if you start reading this manual from the start, and
+skip to the next chapter when you get bored, you will get a reasonable
+overview of the available modules and application areas that are
+supported by the Python library.  Of course, you don't \emph{have} to
+read it like a novel --- you can also browse the table of contents (in
+front of the manual) or look for a specific function, module or term
+in the index (in the back).  And finally, if you enjoy learning about
+random subjects, you choose a random page number (see module
+\code{rand}) and read a section or two.
+
+Let the show begin!