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| -rw-r--r-- | docs/users_guide/exts/qualified_do.rst | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/docs/users_guide/exts/qualified_do.rst b/docs/users_guide/exts/qualified_do.rst index 4a4eabc1b2..71c43c5655 100644 --- a/docs/users_guide/exts/qualified_do.rst +++ b/docs/users_guide/exts/qualified_do.rst @@ -84,14 +84,14 @@ The semantics of ``do`` notation statements with ``-XQualifiedDo`` is as follows M.do { pat <- u; stmts } = u M.>>= \case pat -> M.do { stmts } -* The desugaring of ``-XApplicativeDo`` uses ``(M.<$>)``, ``(M.<*>)``, +* The desugaring of ``-XApplicativeDo`` uses ``M.fmap``, ``(M.<*>)``, and ``M.join`` (after the the applicative-do grouping has been performed) :: M.do { (x1 <- u1 | … | xn <- un); M.return e } = - (\x1 … xn -> e) M.<$> u1 M.<*> … M.<*> un + (\x1 … xn -> e) `M.fmap` u1 M.<*> … M.<*> un M.do { (x1 <- u1 | … | xn <- un); stmts } = - M.join ((\x1 … xn -> M.do { stmts }) M.<$> u1 M.<*> … M.<*> un) + M.join ((\x1 … xn -> M.do { stmts }) `M.fmap` u1 M.<*> … M.<*> un) Note that ``M.join`` is only needed if the final expression is not identifiably a ``return``. With ``-XQualifiedDo`` enabled, ``-XApplicativeDo`` |