diff options
| -rw-r--r-- | docs/users_guide/glasgow_exts.xml | 33 |
1 files changed, 16 insertions, 17 deletions
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml index 3407de5d1d..c97489b781 100644 --- a/docs/users_guide/glasgow_exts.xml +++ b/docs/users_guide/glasgow_exts.xml @@ -3071,12 +3071,11 @@ selectors. Here is the example of that section, in GADT-style syntax: <programlisting> data Counter a where - NewCounter { _this :: self - , _inc :: self -> self - , _display :: self -> IO () - , tag :: a - } - :: Counter a + NewCounter :: { _this :: self + , _inc :: self -> self + , _display :: self -> IO () + , tag :: a + } -> Counter a </programlisting> As before, only one selector function is generated here, that for <literal>tag</literal>. Nevertheless, you can still use all the field names in pattern matching and record construction. @@ -3188,17 +3187,17 @@ As mentioned in <xref linkend="gadt-style"/>, record syntax is supported. For example: <programlisting> data Term a where - Lit { val :: Int } :: Term Int - Succ { num :: Term Int } :: Term Int - Pred { num :: Term Int } :: Term Int - IsZero { arg :: Term Int } :: Term Bool - Pair { arg1 :: Term a - , arg2 :: Term b - } :: Term (a,b) - If { cnd :: Term Bool - , tru :: Term a - , fls :: Term a - } :: Term a + Lit :: { val :: Int } -> Term Int + Succ :: { num :: Term Int } -> Term Int + Pred :: { num :: Term Int } -> Term Int + IsZero :: { arg :: Term Int } -> Term Bool + Pair :: { arg1 :: Term a + , arg2 :: Term b + } -> Term (a,b) + If :: { cnd :: Term Bool + , tru :: Term a + , fls :: Term a + } -> Term a </programlisting> However, for GADTs there is the following additional constraint: every constructor that has a field <literal>f</literal> must have |