Hi, Am Donnerstag, den 16.08.2018, 08:46 +0000 schrieb Simon Peyton Jones via ghc-steering-committee:
What would be ambiguous is this and-pattern: Nothing @ pat (i.e. with a nullary contructor as the first of p1@p2). But that's a pretty silly and-pattern so I think we could let this ambiguous case resolve as a pattern type application.
nullary constructors can be synonyms! pattern Ascii :: String pattern Ascii <- (all isAscii -> True) and now foo (Ascii @ ('X':rest)) = is now longer as silly…
You could I suppose write (Nothing)@pat to get the and-pattern.
Significant parenthesis? Ugh. But yeah, maybe it is good enough™ to deal with this particular corner. Cheers, Joachim -- Joachim Breitner mail@joachim-breitner.de http://www.joachim-breitner.de/