Ki-Wing Ho and Eric Fox
Computer Science 429b
Professor Hudak
Final Project:  User Manual


Control Commands:


(DO <clause> WHILE <cond>)

   Loop, executing a list of commands, then checking a condition and
looping again if the condition is true.


(REPEAT n TIMES)
  WHILE cn cl
  IF cn THEN cl1 [ELSE cl2]

Load a file:
  USE "filename

Environment Commands:
  MAKE "nm v
  LOCAL "nm
  TO :nm1 :nm2 :nm3 ... cl

Text I/O:
  PRINT v
  READ

Graphics Commands:
  FORWARD n
  BACKWARD n
  SETXY n1 n2
  LEFT n
  RIGHT n
  PENUP
  PENDOWN
  HIDETURTLE
  SHOWTURTLE
  CLEARSCREEN
  CLEAN

Graphics Functions:
  XCOR
  YCOR
  GETANGLE
  GETPEN
  GETTURTLE

Mathematical:
  SUM n1 n2
  DIFFERENCE n1 n2
  PRODUCT n1 n2
  MOD n1 n2
  DIV n1 n2
  POWER n1 n2

Boolean:
  AND b1 b2
  OR b1 b2
  NOT b

Predicates:
  WORDP v
  LISTP v
  NUMBERP v
  GREATER n1 n2
  LESS n1 n2
  EQUAL v1 v2
  
Word/List:
  FIRST t
  LAST t
  FPUT t l
  BUTFIRST l
  WORD w1 w2 w3 ...
  LIST t1 t2 t3 ...
  CONCAT l1 l2
  SENTENCE t1 t2 t3 ...


Our Logo interpreter will only support one of the three windowing
modes: window mode, where the turtle, if it walks off the end of the
screen, just continues going and does not wrap.  The two (unsupported)
modes are fence mode where the turtle cannot walk off the end, and
wrap mode.  The initial turtle state will be with the turtle hidden,
the pen down, and the turtle in the center of the screen facing
upwards.

All input (both for commands as well as user-input) will be
case-insensitive, and the interpreter needs to handle lists, words,
integers, and boolean values.  Also, typing "GoodBye" at the LOGO>
prompt exits the interpreter.

All commands will be enclosed in parentheses, and all lists of
commands will be enclosed in square brackets, so that there is no
longer any need for the keyword "End". Also, all procedures will
return the value of their last command, so that there are no Stop or
Output commands.  IF statements should return the value of the last
statement executed, but all looping constructs should return no value.