:: VarDef = VarDef String [FieldSelector]
:: FieldSelector = FieldHd | FieldTl | FieldFst | FieldSnd
:: Op1 = UnNegation | UnMinus
:: Op2 = BiPlus | BiMinus | BiTimes | BiDivide | BiMod | BiEquals | BiLesser |
BiGreater | BiLesserEq | BiGreaterEq | BiUnEqual | BiAnd | BiOr | BiCons
:: VarDef = VarDef String [FieldSelector]
:: FieldSelector = FieldHd | FieldTl | FieldFst | FieldSnd
:: Op1 = UnNegation | UnMinus
:: Op2 = BiPlus | BiMinus | BiTimes | BiDivide | BiMod | BiEquals | BiLesser |
BiGreater | BiLesserEq | BiGreaterEq | BiUnEqual | BiAnd | BiOr | BiCons