share/macro/caseq.mac

   1 /*-*-Macsyma-*-*/
   2
   3
   4 /*
   5 CASEQ(<var>,'[<keys1>],<stmt1>,
   6             '[<keys2>],<stmt2>,
   7             ....,
   8             '[<keysn>],<stmtn>
   9             {,'otherwise,<code for no match>})
  10
  11 where the first <stmt> that has <var> as a member of the associated
  12 <keys> is the one chosen to execute.  */
  13
  14
  15 sstatus(feature,"gcook caseq")$
  16
  17 caseq(var,[pairs])::=
  18    if length(pairs)<=2 then
  19       block([keys:first(pairs),statement:last(pairs)],
  20          if keys=otherwise then buildq([var,statement],statement)
  21          else buildq([var,keys,statement],if member(var,'keys) then statement))
  22    else buildq([var,keys:first(pairs),statement:first(rest(pairs)),
  23                 pairs:rest(rest(pairs))],
  24           if member(var,'keys) then statement else caseq(var,splice(pairs)))$
  25