id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
1404	allow more type signatures	Isaac Dupree		"(idea triggered by #393)

Allow multiple copies of a type-signature in a module, such that it is an error if they're not equivalent, but they don't have to be syntactically equal (
{{{f :: ShowS}}}
{{{f :: String -> String}}}
is okay).

It would also be nice to allow any name in scope at top-level (even if imported) to be given a type signature.  But that raises a question: can these type signatures give a more specific type than that of the raw imported function, the way normal function type signatures can with regards to their implementation?

Use cases: (1. making sure multiple implementations give the same interface, generally varying by #ifdef) (2. asserting that something's type can be specified in two different weird ways).  I don't really want to abandon having a type-signature right above every function definition even if it is a duplicate.

(1.) would be fixed by allowing type signatures in export lists instead.  I suppose these could be more restrictive than in the module and not affect the module, e.g. 
{{{
module X (idN :: Int -> Int, true) where
idN n = n
true :: Bool
true = idN True
}}}"	feature request	new	normal	_|_	Compiler (Type checker)	6.6.1				Unknown/Multiple	Unknown/Multiple	None/Unknown	Unknown