[
  ["type", "ID", "String"],
  ["type", "NUM", "Integer"],
  ["type", "STRING", "String"],
  ["data", "Main",
    ["Main", ["definitions", ["*", "Definition"]]]
  ],
  ["data", "Definition",
    ["DefProgram", ["body", "Statement"]],
    ["DefInteractiveProgram", ["branches", ["*", "SwitchBranch"]]],
    ["DefProcedure", ["name", "ID"], ["parameters", ["*", "ID"]], ["body", "Statement"]],
    ["DefFunction", ["name", "ID"], ["parameters", ["*", "ID"]], ["body", "Statement"]],
    ["DefType", ["typeName", "ID"], ["constructorDeclarations", ["*", "ConstructorDeclaration"]]]
  ],
  ["data", "Statement",
    ["StmtBlock", ["statements", ["*", "Statement"]]],
    ["StmtReturn", ["result", "Expression"]],
    ["StmtIf", ["condition", "Expression"], ["thenBlock", "Statement"], ["elseBlock", ["?", "Statement"]]],
    ["StmtRepeat", ["times", "Expression"], ["body", "Statement"]],
    ["StmtForeach", ["pattern", "Pattern"], ["range", "Expression"], ["body", "Statement"]],
    ["StmtWhile", ["condition", "Expression"], ["body", "Statement"]],
    ["StmtSwitch", ["subject", "Expression"], ["branches", ["*", "SwitchBranch"]]],
    ["StmtAssignVariable", ["variable", "ID"], ["value", "Expression"]],
    ["StmtAssignTuple", ["variables", ["*", "ID"]], ["value", "Expression"]],
    ["StmtProcedureCall", ["procedureName", "ID"], ["args", ["*", "Expression"]]]
  ],
  ["data", "SwitchBranch",
    ["SwitchBranch", ["pattern", "Pattern"], ["body", "Statement"]]
  ],
  ["data", "Pattern",
    ["PatternWildcard"],
    ["PatternVariable", ["variableName", "ID"]],
    ["PatternNumber", ["number", "NUM"]],
    ["PatternStructure", ["constructorName", "ID"], ["parameters", ["*", "ID"]]],
    ["PatternTuple", ["parameters", ["*", "ID"]]],
    ["PatternTimeout", ["timeout", "NUM"]]
  ],
  ["data", "Expression",
    ["ExprVariable", ["variableName", "ID"]],
    ["ExprConstantNumber", ["number", "NUM"]],
    ["ExprConstantString", ["string", "STRING"]],
    ["ExprChoose", ["condition", "Expression"], ["trueExpr", "Expression"], ["falseExpr", "Expression"]],
    ["ExprMatching", ["subject", "Expression"], ["branches", ["*", "MatchingBranch"]]],
    ["ExprList", ["elements", ["*", "Expression"]]],
    ["ExprRange", ["first", "Expression"], ["second", ["?", "Expression"]], ["last", "Expression"]],
    ["ExprTuple", ["elements", ["*", "Expression"]]],
    ["ExprStructure", ["constructorName", "ID"], ["fieldBindings", ["*", "FieldBinding"]]],
    ["ExprStructureUpdate", ["constructorName", "ID"], ["original", "Expression"], ["fieldBindings", ["*", "FieldBinding"]]],
    ["ExprFunctionCall", ["functionName", "ID"], ["args", ["*", "Expression"]]]
  ],
  ["data", "MatchingBranch",
    ["MatchingBranch", ["pattern", "Pattern"], ["body", "Expression"]]
  ],
  ["data", "ConstructorDeclaration",
    ["ConstructorDeclaration", ["constructorName", "ID"], ["fieldNames", ["*", "ID"]]]
  ],
  ["data", "FieldBinding",
    ["FieldBinding", ["fieldName", "ID"], ["value", "Expression"]]
  ]
]