Updating Records in Elm

chess_piece.elm

data Color = Black | White
data Piece = Pawn | Knight | Bishop | Rook | Queen | King

blackQueen = { color=Black, piece=Queen }
-- { color = Black, piece = Queen } : {color : Color, piece : Piece}

-- instantiating the record creates functions to return it's attributes:

.color blackQueen
-- Black : Color

-- There's also some syntactic sugar to call the function like a method:

blackQueen.color
-- Black : Color

-- Updating the record

whiteQueen = { blackQueen | color <- White }
-- { color = White, piece = Queen } : {piece : Piece, color : Color}

position = { column = "d", row = 1 }
-- { column = "d", row = 1 } : {column : String, row : number}

homeWhiteQueen = { whiteQueen | position = position }
-- { color = White, piece = Queen, position = { column = "d", row = 1 } } : {piece : Piece, color : Color, position : {column : String, row : number}}

colorAndPosition = { homeWhiteQueen - piece }
-- { color = White, position = { column = "d", row = 1 } } : {b | position : {column : String, row : number}}