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+# Experimental!
+# shogi game core
+
+┌─╴Piece
+  ~ {Type Side}
+  ┌─╴Type
+    |Pawn |PPawn
+    |Rook |Dragon
+    |Bishop |Horse
+    |Lance |PLance
+    |Knight |PKnight
+    |Silver |PSilver
+    |Gold
+    |King
+  └─╴
+  ┌─╴Side
+    |Sente |Gote
+  └─╴
+└─╴
+
+# translates between equivalent board string
+# notation and internal structure
+┌─╴Representation
+  # the standard initial board, in string form
+  STARTINGBOARDSTRING ← $  l n s g k g s n l
+                        $  . b . . . . . r .
+                        $  p p p p p p p p p
+                        $  . . . . . . . . .
+                        $  . . . . . . . . .
+                        $  . . . . . . . . .
+                        $  P P P P P P P P P
+                        $  . R . . . . . B .
+                        $  L N S G K G S N L
+
+  # OptionalPiece ? PieceString
+  FromString ↚ (
+    # order matters!
+    Notation ↚ [" P" "+P" " R" "+R" " B" "+B" " L" "+L" " N" "+N" " S" "+S" " G" " K"]
+    ∊Notation⊸⌵
+    ⨬(⋅[] # empty tile
+    | Piece ⊃(
+        ⊗Notation⌵
+        ⨬(Piece.Type.Pawn | Piece.Type.PPawn
+        | Piece.Type.Rook | Piece.Type.Dragon
+        | Piece.Type.Bishop | Piece.Type.Horse
+        | Piece.Type.Lance | Piece.Type.PLance
+        | Piece.Type.Knight | Piece.Type.PKnight
+        | Piece.Type.Silver | Piece.Type.PSilver
+        | Piece.Type.Gold
+        | Piece.Type.King
+        )
+      | ⨬(Piece.Side.Gote|Piece.Side.Sente)≍⊸⌵
+      )
+    )
+  )
+
+  # PieceString ? Piece
+  ToString ↚ (
+    ≠0⊸⧻
+    ⨬(⋅" ."
+    | °Piece
+      ⍡(" P" ⍩°Piece.Type.Pawn | "+P" ⍩°Piece.Type.PPawn
+      | " R" ⍩°Piece.Type.Rook | "+R" ⍩°Piece.Type.Dragon
+      | " B" ⍩°Piece.Type.Bishop | "+B" ⍩°Piece.Type.Horse
+      | " L" ⍩°Piece.Type.Lance | "+L" ⍩°Piece.Type.PLance
+      | " N" ⍩°Piece.Type.Knight | "+N" ⍩°Piece.Type.PKnight
+      | " S" ⍩°Piece.Type.Silver | "+S" ⍩°Piece.Type.PSilver
+      | " G" ⍩°Piece.Type.Gold
+      | " K" ⍩°Piece.Type.King
+      )
+      ˜⍥¯
+    )
+  )
+
+  PieceString ← ⌅(ToString|FromString)
+  ArrayString ← ⌅(≡₀◇ToString|⍚₁FromString)
+  BoardString ← ⌅(
+    ArrayString
+    /$"_\n_" ≡/⊂
+  | ⊜(⬚@ ↯∞_2)⊸≠@\n
+    °ArrayString
+  )
+  PrintBoardString ← (
+    &p" 9 8 7 6 5 4 3 2 1|"
+    &p"------------------+--"
+    ⊜∘⊸≠@\n
+    ≡⊂@|⍉¤"一二三四五六七八九"
+    ≡&p˜≡⊂
+  )
+└─╴
+
+Representation!(
+  STARTINGBOARDSTRING
+  ⍜°BoardString(∘)
+  PrintBoardString
+)