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|  ____  ____  _     ___ _   _ _____                              |
| / ___||  _ \| |   |_ _| \ | | ____|  _ _                        |
| \___ \| |_) | |    | ||  \| |  _|   (_|_)                       |
|  ___) |  __/| |___ | || |\  | |___   _ _   Simple Portable      |
| |____/|_|   |_____|___|_| \_|_____| (_|_)  LISP Interpreter     |
|                                                                 |
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*** Operating Environment
=========================
  Primary target platforms: BSD UNIX, DEC OpenVMS
  Should be working on: GNU Linux, MS Windows, Apple MacOS X

*** Built-in functions
======================
  (1) List and dotted pair operations: CAR, CDR, CONS, LIST
      Well known actions:
      (a) (CAR (list 1 2 3 4)) returns 1
      (b) (CDR (list 1 2 3 4)) returns (2 3 4)
      (c) (CONS 1 2) returns (1 . 2) -- dotted pair creator
      (d) (LIST 'a 'b 3 4) returns (A B 3 4) -- list creator

  (2) Number operations: +, *, -, /, %, <, >, =, <=, >=
      Apply lambda operation on all arguments specified.
      For example: (% (* 1 2 3 4 (+ 2 2 1)) 20) returns 0, because
      ((1*2*3*4*(2+2+1)) mod 20) is exactly zero

  (3) Object operations: IS (compare references of two objects)

  (4) Logical AND/OR
  (5) READ(LN)/WRITE(LN) -- basic I/O
Note: (4) and (5) haven't been implemented yet

*** Built-in special forms
==========================
  (1) Well known SETQ, QUOTE, COND, LOAD, LAMBDA, SPECIAL and LET
      (a) (SETQ A 10) creates new variable atom of value 10 and returns 10
      (b) (QUOTE HELLO) is the full form for 'HELLO, this returns HELLO
          without any evaluation
      (c) (COND ((= a 1) 'A-IS-ONE)
                ((= a 2) 'A-IS-TWO)
                (T 'A-IS-NOT-ONE-OR-TWO))
          This prints A-IS-ONE it the A variable is 1, A-IS-TWO for a=2,
          otherwise A-IS-NOT-ONE-OR-TWO, because the result of all previous
          conditions was NIL.
      (d) (LOAD "path/to/some/file.lisp") will read commands in file.lisp
      (e) ((LAMBDA (X Y) (LIST 'X '= X 'AND 'Y '= Y)) 10 20) prints out
          (X = 10 AND Y = 20). This is unnamed lambda function, which can be
          "named" using SETQ:
            (SETQ MY-FUN (LAMBDA (X Y) (LIST 'X '= X 'AND 'Y '= Y)))
          and then called as: (MY-FUN 10 20) with the same result.
          The situation is similar for SPECIAL with exception that arguments
          will not be evaluated when the function is called.
      (f) (LET ((X 10) (Y 20)) (CONS X Y)) creates "local" variables X and Y,
          bound to 10 and 20 only from view of it's body -- (CONS X Y).
          It means that the result will be (10 . 20) independently
          on a "global" meaning of X and Y.

  (2) ISDEFINED -- returns NIL if the argument is an atom of type Undefined,
      otherwise returns T.

  (3) ISATOM, ISLIST, ISNUMBER -- check type of argument's value
  (4) BODY -- print the body of function
  (5) SHOW-MEM -- print a memory dump. Default is brief three-line statistics.
      When the FULL argument is supplied, it prints complete memory listing.
  (6) GETLPI -- LISP Process Informations: an equivalent to VMS-like $GETJPI
      Supported items: ATOMS_USED, LISTS_USED, NUMBERS_USED, MAXATOMS,
                       MAXLISTS, MAXNUMBERS, MODE.

*** Built-in ordinary atoms
===========================
  (1) Standard T and NIL
  (2) Special number values: INF and NaN

*** Data types
==============
  (1) Numbers (double precision)
  (2) Ordinary atoms
  (3) Lists
  (4) Strings -- in form " some string context " -- in atom table,
      returns itself, "" (an empty string) is evaluated to NIL

*** Internal options
====================
Each option is enabled just when it is set to a T value. If the option
is not defined or is defined to any non-T value, it's disabled;

  (1) LISP$LOG   -- enable logging of all %LISP-* messages; not set by default
  (2) LISP$TRACE -- print sub-results while evaluating; not set by default
  (3) LISP$GC    -- enable garbage collection; default is T

*** Friendly syntax error tracing
=================================
  Syntactic errors are traced as in the following example:
    --> (hello world `)
    %LISP-W-BADSYN, Bad syntax!
     (hello world `)
    ..............^
    -->
  it's much better than "syntax error on position 14" message
  which is typical on many compilers/interpreters/whatever...
  With this feature you can easily track similar typo.

*** Examples
============
Example scripts are startup.lisp and test.lisp.
startup.lisp is loaded automatically if it's in your current working directory
from which you are starting the LISP program.