-- Andreas, 2021-04-24
-- Strict category checking in list rules.

-- Bad:
(:[]).  [Exp] ::= Exp1 "end";           -- Exp1 only allowed in [Exp1]
(:).    [Exp] ::= Exp1 "then" [Exp];    -- Exp1 only allowed in [Exp1]

-- Also bad:
(:[]).  [Exp1] ::= Exp "end";           -- Exp only allowed in [Exp]
(:).    [Exp1] ::= Exp "then" [Exp1];   -- Exp only allowed in [Exp]

-- -- Good:
-- (:[]).  [Exp1] ::= Exp1 "end";          -- Exp1 only allowed in [Exp1]
-- (:).    [Exp1] ::= Exp1 "then" [Exp1];  -- Exp1 only allowed in [Exp1]

EInt.   Exp1 ::= Integer;
EPlus.  Exp  ::= Exp "+" Exp1;

coercions Exp 1;