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version 1.140, 2005/07/27 10:23:10 version 1.141, 2005/10/02 11:30:33
Line 1294  You can print the top of stack element w Line 1294  You can print the top of stack element w
 In general, words consume their stack arguments (@code{.s} is an  In general, words consume their stack arguments (@code{.s} is an
 exception).  exception).
   
 @assignment  @quotation Assignment
 What does the stack contain after @code{5 6 7 .}?  What does the stack contain after @code{5 6 7 .}?
 @endassignment  @end quotation
   
   
 @node Arithmetics Tutorial, Stack Manipulation Tutorial, Stack Tutorial, Tutorial  @node Arithmetics Tutorial, Stack Manipulation Tutorial, Stack Tutorial, Tutorial
Line 1327  operands: Line 1327  operands:
 3 4 5 * + .  3 4 5 * + .
 @end example  @end example
   
 @assignment  @quotation Assignment
 What are the infix expressions corresponding to the Forth code above?  What are the infix expressions corresponding to the Forth code above?
 Write @code{6-7*8+9} in Forth notation@footnote{This notation is also  Write @code{6-7*8+9} in Forth notation@footnote{This notation is also
 known as Postfix or RPN (Reverse Polish Notation).}.  known as Postfix or RPN (Reverse Polish Notation).}.
 @endassignment  @end quotation
   
 To change the sign, use @code{negate}:  To change the sign, use @code{negate}:
   
Line 1339  To change the sign, use @code{negate}: Line 1339  To change the sign, use @code{negate}:
 2 negate .  2 negate .
 @end example  @end example
   
 @assignment  @quotation Assignment
 Convert -(-3)*4-5 to Forth.  Convert -(-3)*4-5 to Forth.
 @endassignment  @end quotation
   
 @code{/mod} performs both @code{/} and @code{mod}.  @code{/mod} performs both @code{/} and @code{mod}.
   
Line 1380  Two more stack manipulation words are: Line 1380  Two more stack manipulation words are:
 1 2 .s tuck .s 2drop drop  1 2 .s tuck .s 2drop drop
 @end example  @end example
   
 @assignment  @quotation Assignment
 Replace @code{nip} and @code{tuck} with combinations of other stack  Replace @code{nip} and @code{tuck} with combinations of other stack
 manipulation words.  manipulation words.
   
Line 1398  Given:          How do you get: Line 1398  Given:          How do you get:
 1 2 3           1 2 3 4                   1 2 3           1 2 3 4                 
 1 2 3           1 3               1 2 3           1 3             
 @end example  @end example
 @endassignment  @end quotation
   
 @example  @example
 5 dup * .  5 dup * .
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write 17^3 and 17^4 in Forth, without writing @code{17} more than once.  Write 17^3 and 17^4 in Forth, without writing @code{17} more than once.
 Write a piece of Forth code that expects two numbers on the stack  Write a piece of Forth code that expects two numbers on the stack
 (@var{a} and @var{b}, with @var{b} on top) and computes  (@var{a} and @var{b}, with @var{b} on top) and computes
 @code{(a-b)(a+1)}.  @code{(a-b)(a+1)}.
 @endassignment  @end quotation
   
 Reference: @ref{Stack Manipulation}.  Reference: @ref{Stack Manipulation}.
   
Line 1529  it in other definitions: Line 1529  it in other definitions:
 3 fourth-power .  3 fourth-power .
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write colon definitions for @code{nip}, @code{tuck}, @code{negate}, and  Write colon definitions for @code{nip}, @code{tuck}, @code{negate}, and
 @code{/mod} in terms of other Forth words, and check if they work (hint:  @code{/mod} in terms of other Forth words, and check if they work (hint:
 test your tests on the originals first).  Don't let the  test your tests on the originals first).  Don't let the
 @samp{redefined}-Messages spook you, they are just warnings.  @samp{redefined}-Messages spook you, they are just warnings.
 @endassignment  @end quotation
   
 Reference: @ref{Colon Definitions}.  Reference: @ref{Colon Definitions}.
   
Line 1582  more complicated words (I usually do thi Line 1582  more complicated words (I usually do thi
 you have to work through every definition before you can understand  you have to work through every definition before you can understand
 any).  any).
   
 @assignment  @quotation Assignment
 The stack effect of @code{swap} can be written like this: @code{x1 x2 --  The stack effect of @code{swap} can be written like this: @code{x1 x2 --
 x2 x1}.  Describe the stack effect of @code{-}, @code{drop}, @code{dup},  x2 x1}.  Describe the stack effect of @code{-}, @code{drop}, @code{dup},
 @code{over}, @code{rot}, @code{nip}, and @code{tuck}.  Hint: When you  @code{over}, @code{rot}, @code{nip}, and @code{tuck}.  Hint: When you
 are done, you can compare your stack effects to those in this manual  are done, you can compare your stack effects to those in this manual
 (@pxref{Word Index}).  (@pxref{Word Index}).
 @endassignment  @end quotation
   
 Sometimes programmers put comments at various places in colon  Sometimes programmers put comments at various places in colon
 definitions that describe the contents of the stack at that place (stack  definitions that describe the contents of the stack at that place (stack
Line 1643  Float (on the FP stack) Line 1643  Float (on the FP stack)
   
 You can find a more complete list in @ref{Notation}.  You can find a more complete list in @ref{Notation}.
   
 @assignment  @quotation Assignment
 Write stack-effect comments for all definitions you have written up to  Write stack-effect comments for all definitions you have written up to
 now.  now.
 @endassignment  @end quotation
   
   
 @node Types Tutorial, Factoring Tutorial, Stack-Effect Comments Tutorial, Tutorial  @node Types Tutorial, Factoring Tutorial, Stack-Effect Comments Tutorial, Tutorial
Line 1823  into stack trouble.  However, I recommen Line 1823  into stack trouble.  However, I recommen
 definitions without locals for exercise purposes to help you gain the  definitions without locals for exercise purposes to help you gain the
 essential factoring skills.  essential factoring skills.
   
 @assignment  @quotation Assignment
 Rewrite your definitions until now with locals  Rewrite your definitions until now with locals
 @endassignment  @end quotation
   
 Reference: @ref{Locals}.  Reference: @ref{Locals}.
   
Line 1881  You can optionally use an @code{else}-pa Line 1881  You can optionally use an @code{else}-pa
 3 2 min .  3 2 min .
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write @code{min} without @code{else}-part (hint: what's the definition  Write @code{min} without @code{else}-part (hint: what's the definition
 of @code{nip}?).  of @code{nip}?).
 @endassignment  @end quotation
   
 Reference: @ref{Selection}.  Reference: @ref{Selection}.
   
Line 1958  operation of the Boolean operations to a Line 1958  operation of the Boolean operations to a
 1 foo .  1 foo .
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write @code{min} without @code{if}.  Write @code{min} without @code{if}.
 @endassignment  @end quotation
   
 For reference, see @ref{Boolean Flags}, @ref{Numeric comparison}, and  For reference, see @ref{Boolean Flags}, @ref{Numeric comparison}, and
 @ref{Bitwise operations}.  @ref{Bitwise operations}.
Line 2036  Here's a loop with an exit at the end: Line 2036  Here's a loop with an exit at the end:
 @code{Until} consumes a flag; if it is non-zero, execution continues at  @code{Until} consumes a flag; if it is non-zero, execution continues at
 the @code{begin}, otherwise after the @code{until}.  the @code{begin}, otherwise after the @code{until}.
   
 @assignment  @quotation Assignment
 Write a definition for computing the greatest common divisor.  Write a definition for computing the greatest common divisor.
 @endassignment  @end quotation
   
 Reference: @ref{Simple Loops}.  Reference: @ref{Simple Loops}.
   
Line 2082  You can access the counter of a counted Line 2082  You can access the counter of a counted
 There is also @code{+do}, which expects signed numbers (important for  There is also @code{+do}, which expects signed numbers (important for
 deciding whether to enter the loop).  deciding whether to enter the loop).
   
 @assignment  @quotation Assignment
 Write a definition for computing the nth Fibonacci number.  Write a definition for computing the nth Fibonacci number.
 @endassignment  @end quotation
   
 You can also use increments other than 1:  You can also use increments other than 1:
   
Line 2144  For recursive definitions you can use @c Line 2144  For recursive definitions you can use @c
 8 fac2 .  8 fac2 .
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write a recursive definition for computing the nth Fibonacci number.  Write a recursive definition for computing the nth Fibonacci number.
 @endassignment  @end quotation
   
 Reference (including indirect recursion): @xref{Calls and returns}.  Reference (including indirect recursion): @xref{Calls and returns}.
   
Line 2244  You cannot mix using locals and using th Line 2244  You cannot mix using locals and using th
 standard; Gforth has no problem).  However, they solve the same  standard; Gforth has no problem).  However, they solve the same
 problems, so this shouldn't be an issue.  problems, so this shouldn't be an issue.
   
 @assignment  @quotation Assignment
 Can you rewrite any of the definitions you wrote until now in a better  Can you rewrite any of the definitions you wrote until now in a better
 way using the return stack?  way using the return stack?
 @endassignment  @end quotation
   
 Reference: @ref{Return stack}.  Reference: @ref{Return stack}.
   
Line 2308  . Line 2308  .
 v3 5 cells dump  v3 5 cells dump
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write a definition @code{vsum ( addr u -- n )} that computes the sum of  Write a definition @code{vsum ( addr u -- n )} that computes the sum of
 @code{u} cells, with the first of these cells at @code{addr}, the next  @code{u} cells, with the first of these cells at @code{addr}, the next
 one at @code{addr cell+} etc.  one at @code{addr cell+} etc.
 @endassignment  @end quotation
   
 You can also reserve memory without creating a new word:  You can also reserve memory without creating a new word:
   
Line 2416  type Line 2416  type
 type  type
 @end example  @end example
   
 @assignment  @quotation Assignment
 @code{Emit ( c -- )} types @code{c} as character (not a number).  @code{Emit ( c -- )} types @code{c} as character (not a number).
 Implement @code{type ( addr u -- )}.  Implement @code{type ( addr u -- )}.
 @endassignment  @end quotation
   
 Reference: @ref{Memory Blocks}.  Reference: @ref{Memory Blocks}.
   
Line 2575  Likewise, you can put that into definiti Line 2575  Likewise, you can put that into definiti
 : close-output ( -- )  fd-out close-file throw ;  : close-output ( -- )  fd-out close-file throw ;
 @end example  @end example
   
 @assignment  @quotation Assignment
 How could you modify @code{copy-file} so that it copies until a second line is  How could you modify @code{copy-file} so that it copies until a second line is
 matched? Can you write a program that extracts a section of a text file,  matched? Can you write a program that extracts a section of a text file,
 given the line that starts and the line that terminates that section?  given the line that starts and the line that terminates that section?
 @endassignment  @end quotation
   
 @node Interpretation and Compilation Semantics and Immediacy Tutorial, Execution Tokens Tutorial, Files Tutorial, Tutorial  @node Interpretation and Compilation Semantics and Immediacy Tutorial, Execution Tokens Tutorial, Files Tutorial, Tutorial
 @section Interpretation and Compilation Semantics and Immediacy  @section Interpretation and Compilation Semantics and Immediacy
Line 2789  exception, the stacks have the same dept Line 2789  exception, the stacks have the same dept
 3 2 ' / catch .s  3 2 ' / catch .s
 @end example  @end example
   
 @assignment  @quotation Assignment
 Try the same with @code{execute} instead of @code{catch}.  Try the same with @code{execute} instead of @code{catch}.
 @endassignment  @end quotation
   
 @code{Throw} always jumps to the dynamically next enclosing  @code{Throw} always jumps to the dynamically next enclosing
 @code{catch}, even if it has to leave several call levels to achieve  @code{catch}, even if it has to leave several call levels to achieve
Line 2955  foo . Line 2955  foo .
 foo .  foo .
 @end example  @end example
   
 @assignment  @quotation Assignment
 Define @code{defer ( "name" -- )}, which creates a word that stores an  Define @code{defer ( "name" -- )}, which creates a word that stores an
 XT (at the start the XT of @code{abort}), and upon execution  XT (at the start the XT of @code{abort}), and upon execution
 @code{execute}s the XT.  Define @code{is ( xt "name" -- )} that stores  @code{execute}s the XT.  Define @code{is ( xt "name" -- )} that stores
 @code{xt} into @code{name}, a word defined with @code{defer}.  Indirect  @code{xt} into @code{name}, a word defined with @code{defer}.  Indirect
 recursion is one application of @code{defer}.  recursion is one application of @code{defer}.
 @endassignment  @end quotation
   
 Reference: @ref{User-defined Defining Words}.  Reference: @ref{User-defined Defining Words}.
   
Line 3056  You can define @code{ENDIF} in this way: Line 3056  You can define @code{ENDIF} in this way:
   POSTPONE then ; immediate    POSTPONE then ; immediate
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write @code{MY-2DUP} that has compilation semantics equivalent to  Write @code{MY-2DUP} that has compilation semantics equivalent to
 @code{2dup}, but compiles @code{over over}.  @code{2dup}, but compiles @code{over over}.
 @endassignment  @end quotation
   
 @c !! @xref{Macros} for reference  @c !! @xref{Macros} for reference
   
Line 3096  number computed at compile time into the Line 3096  number computed at compile time into the
 see bar  see bar
 @end example  @end example
   
 @assignment  @quotation Assignment
 Write @code{]L} which allows writing the example above as @code{: bar (  Write @code{]L} which allows writing the example above as @code{: bar (
 -- n ) [ 2 2 + ]L ;}  -- n ) [ 2 2 + ]L ;}
 @endassignment  @end quotation
   
 @c !! @xref{Macros} for reference  @c !! @xref{Macros} for reference
   
Line 3269  order Line 3269  order
 Yes, the order of wordlists in the output of @code{order} is reversed  Yes, the order of wordlists in the output of @code{order} is reversed
 from stack comments and the output of @code{.s} and thus unintuitive.  from stack comments and the output of @code{.s} and thus unintuitive.
   
 @assignment  @quotation Assignment
 Define @code{>order ( wid -- )} with adds @code{wid} as first searched  Define @code{>order ( wid -- )} with adds @code{wid} as first searched
 wordlist to the search order.  Define @code{previous ( -- )}, which  wordlist to the search order.  Define @code{previous ( -- )}, which
 removes the first searched wordlist from the search order.  Experiment  removes the first searched wordlist from the search order.  Experiment
 with boundary conditions (you will see some crashes or situations that  with boundary conditions (you will see some crashes or situations that
 are hard or impossible to leave).  are hard or impossible to leave).
 @endassignment  @end quotation
   
 The search order is a powerful foundation for providing features similar  The search order is a powerful foundation for providing features similar
 to Modula-2 modules and C++ namespaces.  However, trying to modularize  to Modula-2 modules and C++ namespaces.  However, trying to modularize
Line 5096  doc-search Line 5096  doc-search
 doc--trailing  doc--trailing
 doc-/string  doc-/string
 doc-bounds  doc-bounds
   doc-pad
   
 @comment TODO examples  @comment TODO examples
   
Line 8872  For ways of storing character strings in Line 8872  For ways of storing character strings in
 doc-key  doc-key
 doc-key?  doc-key?
 doc-ekey  doc-ekey
 doc-ekey?  
 doc-ekey>char  doc-ekey>char
 doc->number  doc-ekey?
 doc->float  
   Gforth recognizes various keys available on ANSI terminals (in MS-DOS
   you need the ANSI.SYS driver to get that behaviour).  These are the
   keyboard events produced by various common keys:
   
   doc-k-left
   doc-k-right
   doc-k-up        
   doc-k-down      
   doc-k-home      
   doc-k-end       
   doc-k-prior
   doc-k-next
   doc-k-insert
   doc-k-delete
   
   The function keys (aka keypad keys) are:
   
   doc-k1
   doc-k2
   doc-k3
   doc-k4
   doc-k5
   doc-k6
   doc-k7
   doc-k8
   doc-k9
   doc-k10
   doc-k11
   doc-k12
   
   Note that K11 and K12 are not as widely available.  The shifted
   function keys are also not very widely available:
   
   doc-s-k8
   doc-s-k1
   doc-s-k2
   doc-s-k3
   doc-s-k4
   doc-s-k5
   doc-s-k6
   doc-s-k7
   doc-s-k8
   doc-s-k9
   doc-s-k10
   doc-s-k11
   doc-s-k12
   
   Words for inputting one line from the keyboard:
   
 doc-accept  doc-accept
 doc-edit-line  doc-edit-line
 doc-pad  
   Conversion words:
   
   doc->number
   doc->float
   
 @comment obsolescent words..  @comment obsolescent words..
   Obsolescent input and conversion words:
   
 doc-convert  doc-convert
 doc-expect  doc-expect
 doc-span  doc-span
Removed from v.1.140  
changed lines
  Added in v.1.141

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