B.A.G.E.L. Language

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Reference: Value resolution and references ​

Many fields in B.A.G.E.L. (move arguments, end results, conditions) accept resolved values: special objects that the engine replaces with a value from the game state or context. Use these in matcher properties, result values, expression arguments, and similar places.

ctxPath ​

Path into ctx (engine context).

  • type: "ctxPath"
  • path: Array of keys, e.g. ["currentPlayer"], ["playOrder"].

Example: type "ctxPath", path ["currentPlayer"] for the current player ID.

contextPath ​

Path into the current evaluation context (e.g. move validation, end check, ForEach loop).

  • type: "contextPath"
  • path: Array of keys/indexes into the context object.

Common context keys: moveArguments (arguments for the current move), originalTarget (the space/entity the player chose), loopTarget (current item in a ForEach), target, results (from condition evaluation, e.g. HasLine matches).

Example: winner from a HasLine result — path into results[0].matches[0][0].entities[0].attributes.player, or use shorthand ownerOfFirstResultEntity.

gamePath ​

Path into the game state G (e.g. bank, _meta).

  • type: "gamePath"
  • path: Array, e.g. ["_meta", "previousPayloads", "jumpChecker", "arguments", "entity"], ["_meta", "passedPlayers", "length"].

Used in: Checkers (same piece must keep jumping; pass count for win).

expression ​

Evaluate a formula with expr-eval.

  • type: "expression"
  • expression: String (e.g. "player == '0' ? -1 : 1", "(currentPlayer + 1) % 2").
  • arguments: Object mapping variable names to resolved values (which can use ctxPath, contextPath, gamePath, etc.).

Used in: Checkers (player-relative coordinates; winner when opponent passed).

relativeCoordinates ​

Resolve to the space at a relative offset from a given space (e.g. “one step up-right”).

  • type: "relativeCoordinates"
  • target — Optional. Defaults to originalTarget in context. Resolves to a space.
  • location — [dx, dy] or a resolved value (e.g. expression that returns different offsets per player).

Used in: Checkers (move/jump directions), Connect Four (space below for “gravity”).

coordinates ​

Absolute coordinates of a space in its parent grid.

  • type: "coordinates"
  • target — Optional. Defaults to originalTarget. Resolves to a space; parent must be a Grid.

Used in: Checkers (king row: e.g. destinationCoordinates[1] == 0 for player 0).

relativePath ​

Path into target.attributes (rule + state of an entity).

  • type: "relativePath"
  • target — Resolved to an entity.
  • path — Array of keys into that entity’s attributes.

parent ​

The parent container of a space or entity (e.g. the grid that contains the space).

  • type: "parent"
  • target — Optional. Defaults to originalTarget.

map ​

Map a set of targets to another value (e.g. “for each space, get this attribute”).

  • type: "map"
  • targets — Condition or resolution that yields multiple targets.
  • mapping — Resolved for each target (with loopTarget in context). Result is the array of mapped values.

mapMax — Same as map but returns only the targets whose mapped value is maximum (e.g. “players with highest score”).

pick ​

Subset of attributes from a resolved entity.

  • type: "pick"
  • target — Resolved to an entity.
  • properties — Array of attribute names.

When documenting or writing game JSON, remember: ctxPath = engine context; contextPath = current B.A.G.E.L. evaluation context (move, end check, loop); gamePath = game state G.