gearsco.de
A chess library for Gleam
Only allow double pawn moves from starting positions
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src/starfish/internal/move.gleam
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src/starfish/internal/move.gleam
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import gleam/bool
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import iv
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import starfish/internal/board
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import starfish/internal/direction.{type Direction}
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let forward_one = direction.in_direction(position, forward)
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let moves = case iv.get(game.board, forward_one) {
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Ok(board.Empty) -> {
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let moves = [Move(from: position, to: forward_one), ..moves]
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let can_double_move = case game.to_move, board.rank(position) {
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board.Black, 6 | board.White, 1 -> True
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_, _ -> False
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}
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use <- bool.guard(!can_double_move, moves)
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let forward_two = direction.in_direction(forward_one, forward)
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case iv.get(game.board, forward_two) {
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Ok(board.Empty) -> [
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Move(from: position, to: forward_one),
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Move(from: position, to: forward_two),
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..moves
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]
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Ok(board.Occupied(_)) | Error(_) -> [
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Move(from: position, to: forward_one),
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..moves
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]
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Ok(board.Empty) -> [Move(from: position, to: forward_two), ..moves]
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Ok(board.Occupied(_)) | Error(_) -> moves
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}
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}
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Ok(board.Occupied(_)) | Error(_) -> moves