Data update

Task/N-queens-problem/Tailspin/n-queens-problem-3.tailspin

@@ -1,4 +1,6 @@
 templates queens
+  data done <=1> local
+
   def n: $;
   templates getRowColumn
     when <?($@queens.freeRows($.r::raw) <=0>)> do 0 !
@@ -14,8 +16,6 @@ templates queens
     @queens.freeMins($p.c::raw - $p.r::raw + $n): $p.val::raw;
   end setRowColumn
 
-  data done <=1>
-
   templates placeQueen
     def c: $;
     row´1 -> #

Task/N-queens-problem/Tailspin/n-queens-problem-4.tailspin

@@ -0,0 +1,52 @@
+queens templates
+  done requires <|=1>
+  failed requires <|=0>
+  n is $;
+  getRowColumn templates
+    when <|?($@queens(freeRows:; $(r:)::raw) matches <|=0>)> do 0 !
+    when <|?($@queens(freeMaxs:; $(r:)::raw + $(c:)::raw) matches <|=0>)> do 0 !
+    when <|?($@queens(freeMins:; $(c:)::raw - $(r:)::raw + $n) matches <|=0>)> do 0 !
+    otherwise 1!
+  end getRowColumn
+
+  setRowColumn sink
+    p is $;
+    @queens(freeRows:; $p(r:)::raw) set $p(val:)::raw;
+    @queens(freeMaxs:; $p(c:)::raw + $p(r:)::raw) set $p(val:)::raw;
+    @queens(freeMins:; $p(c:)::raw - $p(r:)::raw + $n) set $p(val:)::raw;
+  end setRowColumn
+
+  placeQueen templates
+    {c: $, r: 1} -> # !
+    when <|done> do done´1!
+    when <|{c: <|$n + 1..>}> do done´1!
+    when <|{r: <|$n + 1..>}> do failed´0 !
+    when <|?($ -> getRowColumn matches <|=1>)> do
+      current is $;
+      @queens(queenRows:; $(r:)::raw) set $(c:);
+      {$, val: 0} -> !setRowColumn
+      {c: $(c:)::raw + 1, r: 1} -> # -> templates
+        when <|done> do done´1!
+        otherwise
+          {$current, val: 1} -> !setRowColumn
+          {c: $current(c:), r: $current(r:)::raw + 1} !
+      end -> # !
+    otherwise {c: $(c:), r: $(r:)::raw + 1} -> # !
+  end placeQueen
+
+  @ set { freeRows: [1..$n -> 1],
+    freeMaxs: [1..$n*2 -> 1],
+    freeMins: [1..$n*2 -> 1],
+    queenRows: [1..$n -> -1] };
+  1 -> placeQueen -> templates
+    when <|done> do $@queens(queenRows:) !
+    otherwise 'non-existent'!
+  end!
+end queens
+
+'A solution to the 8 queens problem is $:8 -> queens;
+' !
+'A solution to the 4 queens problem is $:4 -> queens;
+' !
+'A solution to the 3 queens problem is $:3 -> queens;
+' !