On Fri, Jun 10, 2011 at 07:20, Simon Meier
Note that the OverloadedStringLiterals together with the 'IsString' instances gives you more than just a nice syntactic abbreviation: the defined string literals are also lifted out of their context and defined as CAFs. Therefore, you can share the conversion from String to <your-type> during the whole run of a program. We exploit that in blaze-html to do escaping and UTF-8 encoding only once. Hence, in some contexts the IsString instances are necessary.
I'm afraid I don't understand this; could you explain the difference between these two definitions? Specifically, why would the OverloadedStrings version be more efficient? ------------------------------------------------------- foo :: Name foo = Name "foo" (Just "urn:bar") Nothing ------------------------------------------------------- ------------------------------------------------------- {-# LANGUAGE OverloadedStrings #-} foo :: Name foo = "{urn:bar}foo" -------------------------------------------------------