Hi, You don't know anything about your a's but that they have FromJSON instances. That in turn means you can get values from aeson parsing functions. Think parseJSON :: Value -> Parser a Could you be more specific about the problem you try to solve? Best Jan Baa <aquagnu@gmail.com> schrieb am Di., 1. Aug. 2017, 10:32:
Hello, List!
I have, for example, function with signature like
fn :: FromJSON a => Map Text a -> BlahBlah
and I want to treat this `a` as String (or `Text`), to read it with `readMaybe`. Am I right that it's impossible? I get error about "...a is rigid type and could not be matched with Text...". But `Text` is `FromJSON` instance. Is it possible to do it (cast, convert, unwrap, etc)?
The problem's source is that early I worked with `Text` values only (getting from HTML form) but now they become any type: int's, bool's, etc).
=== Best regards, Paul _______________________________________________ Beginners mailing list Beginners@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners