Contents

• INTRODUCTION TO SECOND EDITION (Jan 1996)
  • FOR NEW USERS: A TASTE OF POP-11
  • ACKNOWLEDGEMENTS
  • POPLOG INFORMATION AND FTP SITES
  • Sussex Web and FTP addresses
  • The Birmingham Poplog FTP directory
• PREFACE TO THE FIRST EDITION (Sept 1994)
  • Advantages of Pop-11
  • Pop-11 as a teaching language
  • Disadvantages of Pop-11
  • A brief history of Pop-11
  • The Poplog editor VED
  • Interactive programming
  • Declarative and procedural languages
  • The need for procedures
  • Monitors
  • TEACH files and the VED editor
  • The HELP command
  • The REF command
• CHAPTER.1: INTRODUCTION --- THE ROOMS EXAMPLE
  • POP-11 facilities illustrated in this chapter
  • The ROOMS DATABASE Example
  • Preliminary analysis
    • Representing room dimensions using a list of lists
    • Lexical rules for reading programs
    • Printing out the value of "rooms"
    • Defining procedure display_data
    • Defining the subroutine display_room
    • Defining the procedure perim
    • Defining the procedure area
    • Defining volume:
  • "Top down" and "Bottom up" design
  • Exercise on the ROOMS example
  • Searching for information in the "rooms" database
  • Finding several rooms
  • Exercises
  • Type-less higher order procedures
  • POP-11 : A MINIMAL MODEL
    • The syntax of Pop-11.
    • The semantics of Pop-11
    • The Pop-11 "virtual machine"
    • The dictionary
    • Built-in procedures
    • The heap: for structures which may change
    • The procedure call stack
    • The user stack
    • Input and output channels
    • Conclusion
• CHAPTER.2: INTRODUCTION TO THE SYNTAX AND SEMANTICS OF POP-11
  • Internal semantics and external semantics
  • Expressions denote objects. Imperatives denote actions
  • Compile time vs run time processes
  • How a programming language is specified: virtual machines
  • Some Pop-11 data-types and their external forms
    • Two sorts of numbers
    • Words:
    • Strings:
    • Lists:
  • Some Pop-11 actions
    • Assignments in Pop-11 and other languages.
  • Built in and user-defined procedures
  • Errors and error messages
    • Syntactic and semantic errors
  • Comments in Pop-11 programs
  • Pop-11 Expressions: some examples
  • Imperatives: some examples
    • Printing
    • Assignment
    • A few more examples of assignments:
    • Multiple assignment
    • Declarations of dynamic and lexical (static) variables.
    • Declarations may contain initialisations.
    • Variables and constants
    • Using mixed case and underscores in variables
    • Using undeclared variables
    • NOTE on variables for experienced computer scientists:
  • Procedure definitions are initialised identifier declarations
  • Global and local procedure definitions
  • Procedure calls in Pop-11
    • Imperatives end with separators
  • Using infix operators
  • Procedures which produce results
    • Procedure output values and the stack
    • Procedures returning more than one result
  • Exercises
  • Introduction to printing in Pop-11
    • Two forms of print-arrow
    • Other printing procedures
  • Conditionals and conditions
  • Predicates and recognizer procedures
  • Summary of syntactic roles in Pop-11 programs
  • Lexical analysis and the Pop-11 itemiser
  • Itemisation rules in Pop-11
    • Word formation in Pop-11
    • Using the underscore to join letters and sign characters
    • Strings can contain arbitrary characters
    • Character quotes and string quotes
    • Double quotes with single quotes can form arbitrary words
    • Changing Pop-11's "itemiser" rules
  • Revision questions
  • Built in Pop-11 data types
  • Procedures associated with data-types
    • Generic procedures
  • Data creation, memory management and the heap
    • Note for experts
  • List of Pop-11 Data-types
    • Poplog built in data types
  • Further information on built in data types
    • Words
    • The internal representation of words
    • The Pop-11 dictionary
    • Strings
    • Dstrings
    • Idents (identifier records)
    • Types of numbers in Pop-11
    • Integers and Bigintegers
    • Floating point numbers: decimals and ddecimals
    • Ratios use indefinite precision
    • Complex numbers
    • Recognizers for number types: integral, rational, decimal, complex
    • Reading in numbers relative to a base
    • Characters (8 bit integers)
    • Booleans (true and false)
    • Pairs and lists
    • References (single component records, consref, cont).
    • Types of vectors: strings, full vectors, intvecs, shortvecs
    • Standard full vectors
    • Packed integer vectors: intvecs and shortvecs
    • Procedures, closures, arrays, properties
    • closures
    • arrays
    • Using newanyarray to create an array from an intvec
    • properties
    • `Destroy properties'
    • Declaring a variable to be of type procedure
    • Lightweight processes
    • undefs
    • Keys
    • Unique objects: nil, termin, stackmark
    • The empty list []
    • The stream terminator, termin
    • The stack mark, popstackmark
    • Devices
    • External pointers
    • Sections
    • Prolog variables and terms: prologvars, prologterms
    • Data types required for the Poplog X window interface
  • Objectclass - An object oriented extension to Pop-11
    • Further online information
  • Additional information needed to define Pop-11
  • The garbage collector
  • Exercises
• CHAPTER.3: PROCEDURES AND THE STACK
  • Procedures communicate via the stack
  • The DOT-notation for procedure calls
  • Assignment as a two stage operation
  • The stack and arithmetic expressions
  • Implicit uses of the stack
  • Example: implicit uses of the stack when running "perim"
  • Exercises on the stack
  • More examples of uses of the stack
  • "->" does not always represent an assignment
  • The print arrow "=>"
  • The pretty print arrow ==>
  • Using assignment to store something in a structure
  • Invoking the updater of a procedure
  • Other updaters: subscrv, subscrs
  • Using a numerical subscript to access or update a structure
  • updaters, the stack and "explode"
  • Defining updaters
  • Non-destructive assignment "->>"
  • Exercise
  • Multiple assignments
  • Some procedures which work on the stack
  • Clearing items from the stack (erase)
  • Removing unwanted items from the stack
  • Swapping items using the stack
  • Conditionals and the stack
• CHAPTER.4: PROCEDURES IN POP-11
  • Procedures as "first class objects"
  • Other languages able to manipulate procedures
  • Example: creating new procedures from old
  • Using "partial application" to create a closure
  • Using both partial application and procedure composition
  • Exercises on procedure creation and manipulation
  • Using non-procedures (e.g. lists, vectors) as procedures
  • Arrays are procedures in Pop-11
  • Properties as procedures
    • newmapping associates things compared using "="
    • Properties created using newmapping behave like procedures
    • newproperty associates things compared using "=="
    • Properties can be composed using <>, given to maplist, etc.
  • Exercise using properties for the rooms database
  • DEFINING PROCEDURES IN POP-11
  • Using "define <name> = ... enddefine"
  • Specifying the syntactic type of a procedure identifier
  • Executing (calling, running, applying) a procedure
  • Procedures with more than one output local
  • Output locals and the stack
  • Precedence and parentheses
    • Precedences of arithmetical operations
    • Parentheses can override operator precedence
    • Operators associate to left, unless precedence is negative
    • Using identprops to discover precedence
  • Defining new infix procedures
  • Different types of procedures: normal, infix, macros, syntax
    • Infix operators have a " precedence"
    • Macros and syntax words
    • . Syntactic operators
  • Some important constructs used in defining procedures
  • Loops: instructions to do something repeatedly
    • UNTIL <condition> DO <action> ENDUNTIL
    • REPEAT <number> TIMES <action> ENDREPEAT
    • WHILE <condition> DO <action> ENDWHILE
    • `FOR ... ENDFOR' loops
    • . FOR X IN LIST DO <action> ENDFOR;
    • . FOR L ON LIST DO <action> ENDFOR;
    • . FOR X FROM <number> BY <number> TO <number> DO
    • There are several forms of conditionals.
    • . Examples of conditionals
  • Using conditionals to jump out of, or re-start a loop.
    • Re-starting a loop using "nextloop"
    • Other abnormal exit commands
    • "return" can be used to terminate execution of a procedure.
    • Other abnormal exits.
    • Switch statements
  • Other syntactic constructs
  • Tracing procedures
  • Defining macros and syntax words to extend the language.
    • Macros
    • Macros can be recursive
    • Macro arguments are text items, not expressions
    • Using "define :inline" to define the SWAP macro
    • Note on efficiency of macros
    • Syntax procedures
    • Example: defining a syntax word: loop
• CHAPTER.5: NUMERICAL AND LOGICAL FACILITIES IN POP-11
  • Mathematical knowledge presupposed
  • The machine representation of numbers in Poplog
    • Simple items in Pop-11: integers and decimals
    • Compound items in Pop-11
    • Fixed precision and indefinite precision arithmetic
    • Packed integer or decimal numbers
  • Types of numbers in Pop-11
    • decimals and ddecimals
    • Integers, bigintegers, ratios and complex numbers
  • Forming numerical expressions
    • Using a radix other than 10 to represent numbers on input
    • Using pop_pr_radix to control radix used in printing
    • pop_pr_radix, pop_pr_places and pop_pr_exponent
  • Additional facilities for printing numbers
  • Maximum and minimum integer sizes: pop_max_int, pop_min_int
  • The representation of floating point numbers: lib float_parameters
  • Basic arithmetical facilities
  • Arithmetical operators
    • Examples of arithmetical expressions
    • Illustrating the use of // (which produces two results)
    • Binary and unary negation
    • WARNING: division of integers using "/" can produce ratios
  • Infix predicates on numbers
  • Recognizer predicates for number types
  • Coercing numbers from one type to another
  • Other arithmetic procedures
  • Illustrating popradians
  • Other global variables controlling arithmetical computations
    • popdprecision
    • pop_reduce_ratios
  • Miscellaneous operations on integers, ratios, floats
    • checkinteger, gcd_n, lcm_n
    • destratio, numerator, denominator
    • Operations on floats (decimals and ddecimals)
    • intof, fracof, float_digits, float_precision
    • float_decode, float_scale, float_sign
  • Complex Specific Operations
  • random and oneof
  • Additional mathematical functions
  • Exercises
  • Testing for equality and inequality
  • Bitwise (Logical) integer operators
    • Bit accessing procedures for integers
    • Infix and prefix bitwise (logical) operators
    • Unary bitwise negation 126126
    • Bitwise (logical) shift operators
  • Iteration over numbers
    • for num from ... by ... to ... do ... endfor
    • Using fast_for
    • Iterating over non-arithmetical progressions
  • Using external mathematical libraries
• CHAPTER.6: LIST PROCESSING IN POP-11
  • On knowing about lists
  • Why use lists?
    • Lists can contain a mixture of elements of any type in Pop-11
    • Illustrating generality: isinlist
  • Lists vs other representations
  • Lists in AI
  • Constructing lists in Pop-11
    • Lists are constructed using [ ]
    • List brackets quote their contents
    • Unquoting using 94 and
    • 94( ... ) is equivalent to ....
    • Loops can occur in unquoted portions of a list
  • WARNING lists in procedures are not "constants"
    • Creating a truly constant list expression
    • Using lconstant
    • using #_< ... >_# to evaluate an expression at compile time
    • WARNING constant lists can cause strange behaviour
  • Concatenating lists using <>
  • Merging lists using the double up-arrow
  • Lists are a derived data-type
    • Pairs are the primitive datatype used: conspair, front, back
    • destpair(pair) -> (pair_front, pair_back)
    • A chain of pairs ending in [] is a list
    • List expressions are "syntactic sugar"
    • Recursively chaining down list links
    • Recursing down the front and the back of a "tree"
    • Numeric subscripts and lists
    • Iterating down list links
  • Why use "hd" and "tl" instead of "front" and "back" ?
    • The need to hide implementation details
    • using :: instead of conspair
    • The difference between :: and <>
  • Diagrams showing static lists represented as pairs
    • The lack of symmetry between hd and tl
  • Dynamic lists: generators and pdtolist
    • Generator procedures
    • Printing dynamic lists
    • Using gensym to make a dynamic list
    • Note that gensym will be replaced after V14.5
    • Accessing components of dynamic lists: hd, tl, dest
    • null(list) vs list == []
    • The representation of dynamic lists
    • The uses of dynamic lists
    • An example of an infinite list of input
  • Some procedures for manipulating lists
    • cons, conslist, initl, sysconslist
    • allbutfirst, allbutlast
    • dl or explode, destlist
    • applist, maplist, ncmaplist
    • recursive_front
    • expandlist
    • rev and ncrev
    • setfrontlist
    • sort and syssort
    • last, lastpair
    • oneof, shuffle
    • delete, ncdelete
    • flatten and flatlistify
    • length and listlength
    • copy, copylist, copydata, copytree
    • subscrl, fast_subscrl
  • Predicates on lists
    • atom, islist, ispair, islink, null
    • isdynamic
    • member, lmember
    • user defined predicates
  • Iterating on lists
  • Using for ... in ... do .... with lists
    • Using for inside [ ..... ]
  • Iterating over two or more lists
  • Iteration vs Recursion
  • Exercises
  • More exercises on lists
  • Exercises on the meaning of the single and double up-arrows
• CHAPTER.7: THE POP-11 PATTERN MATCHER AND DATABASE
  • The anonymous segment pattern element: "=="
  • Using matches to define a procedure
  • Exercise
  • Use of the matcher to extract the contents of a list
  • The use of "?" variables
    • Example: Using the matcher to define next_item
    • Exercise: define previous_item
  • The matcher arrow "-->"
    • Examples of the use of "-->"
  • Findroom revisited
  • Setting a value ("?") vs Using a value ("94")
  • List pattern matching
  • Describing the shape of a list pattern
  • Using variables in a pattern specification
  • Matching a "segment" of a list
  • Retrieving details of the target list
  • Using a "restriction" to control or check the match
  • Summary of match notations
  • MATCHing on a corpus of lists - the DATABASE concept
  • Adding and removing database items
  • Using "it" to record what was removed
  • Finding items in the database
    • How PRESENT works.
  • Using "it" to record what was matched
  • Retrieving values from within a matching ITEM
  • Using LOOKUP to extract information from the database
  • FOREACH: iterates over all items PRESENT matching a pattern
  • Checking a set of patterns against the database
  • Forevery: simultaneously satisfying a collection of patterns
  • LIB FMATCHES overcomes some limitations of the matcher
• CHAPTER.8 AN AI APPLICATION: A GENERAL PROBLEM SOLVER
  • Procedures to be supplied by users
    • is_goal_state
    • next_states
    • same_state
    • insert_state
    • is_in_list
  • The definition of solve_problem
  • Using solve_problem to solve a simple problem
  • Exercises
• CHAPTER.9 RECORDS, VECTORS AND OBJECTCLASS
  • Records
  • Defining new record types in Pop-11
    • DEFCLASS and RECORDCLASS
    • An example: recordclass point3D
    • When should records be used?
  • Defining new vector types in Pop-11
    • Using DEFCLASS and VECTORCLASS
    • Example of creation of a new vector class.
  • OBJECTCLASS: an Object-Oriented extension to Pop-11
    • Some examples of the use of Objectclass
    • Defining an objectclass method
    • Defining a subclass of a class
• APPENDIX
  • Additional topics and relevant documentation files
  • Overview of REF files
  • VMS DCL or UNIX shell commands in Pop-11
  • ADDITIONAL READING
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