\; Copyright 1998,1999 Zanshin Inc.          <http://www.zanshin.com/>

\; The contents of this file are subject to the Zanshin Public License Version
\; 1.0 (the "License"); you may not use this file except in compliance with the
\; License.  You should have received a copy of the License with Latte; see
\; the file COPYING.  You may also obtain a copy of the License at
\; <http://www.zanshin.com/ZPL.html>.
\; 
\; Software distributed under the License is distributed on an "AS IS" basis,
\; WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
\; for the specific language governing rights and limitations under the
\; License.
\; 
\; The Original Code is Latte.
\; 
\; The Initial Developer of the Original Code is Zanshin, Inc.


\; car - first element of a group
{\def {\car \list}
  {\nth 0 \list}}

\; front - synonym for car
{\def \front \car}

\; back - last element of a group
{\def {\back \list}
  {\nth {\subtract {\length \list} 1} \list}}

\; cdr - all elements of a group except the first
{\def {\cdr \list}
  {\subseq \list 1}}

\; rdc - all elements of a group except the last
{\def {\rdc \list}
  {\subseq \list 0 -1}}

\; group - construct a group from the arguments
{\def {\group \&rest}
  \rest}

\; reverse - reverse top-level group elements
{\def {\reverse \list}
  {\and \list
        {\push-back {\car \list}
                    {\reverse {\cdr \list}}}}}

\; lmap - apply a function to each element of a group
{\def {\lmap \fn \seq}
  {\if \seq
       {\cons {\funcall \fn {\car \seq}}
              {\lmap \fn {\cdr \seq}}}
    {}}}

\; member - test whether an element appears in a group
{\def {\member? \elt \list}
  {\and \list
        {\or {\equal? \elt {\car \list}}
             {\member? \elt {\cdr \list}}}}}

\; zero? - test whether argument is 0
{\def {\zero? \obj}
  {\equal? \obj 0}}

{\def {\compose \f \g}
  {\lambda {\x} {\f {\g \x}}}}

{\def \caar {\compose \car \car}}
{\def \cadr {\compose \car \cdr}}
{\def \cdar {\compose \cdr \car}}
{\def \cddr {\compose \cdr \cdr}}

{\def \defmacro
  {\macro {\params \&body}
   \`{\def \,{\car \params}
       {\macro \,{\cdr \params} \,@\body}}}}

\;  This is a perfectly good definition of \let, but it's slower
\;  than the intrinsic one in definitions.cxx.

\;  {\defmacro {\let \bindings \&body}
\;   \`{{\lambda \,{\lmap \car \bindings} \,@\body}
\;      \,@{\lmap \cadr \bindings}}}

{\defmacro {\letrec \bindings \&body}
 \`{\let \,{\lmap {\lambda {\x} {\group \x {}}}
                  {\lmap \car \bindings}}
     \,@{\lmap {\lambda {\x} \`{\set! \,{\car \x} \,{\cadr \x}}}
               \bindings}
     \,@\body}}

\;  {\defmacro {\while \test \&body}
\;     \`{\letrec {{\fn {\lambda {}
\;                       {\if \,\test
\;                            {\,@\body
\;                             {\fn}}}}}}
\;        {\fn}}}

{\defmacro {\foreach \var \values \&body}
 \`{\let {{\vals \,\values}
          {\,\var {}}}
     {\while \vals
       {\set! \,\var {\car \vals}}
       {\set! \vals {\cdr \vals}}
       \,@\body}}}