diagnostic colors: differentiate between message head and message body
When a diagnostic message is printed, currently the whole message is colored by the "message" color (bold by default). I'd find it useful if the message body and the header could be differentiated (I do like the idea that the header stands out).
Motivation: Consider the following error message,
GHCi, version 18.104.22.16870508: http://www.haskell.org/ghc/ :? for help Prelude> () () <interactive>:1:1: error: • Couldn't match expected type ‘() -> t’ with actual type ‘()’ • The function ‘()’ is applied to one argument, but its type ‘()’ has none In the expression: () () In an equation for ‘it’: it = () () • Relevant bindings include it :: t (bound at <interactive>:1:1)
which by default is all bold, with the
error: part in red. I want the message body to use normal text. Thanks to #13444 (closed) I can achieve that by setting
GHC_COLORS="message=0". However, that setting also affects the initial
<interactive>:1:1 part of the headline, which now looks odd because normal and bold text are mixed.