Instantiating a type with fresh, flexi type variables

[Simon Peyton-Jones]

I'm a bit puzzled that you don't have a *quantified* type, something like
	forall abc.  ty1 -> ... -> tyn -> ty
to instantiate. I'm a bit suspicious about instantiating all the random free variables of a type (or types). We should talk now I'm back in circulation.   What time zone are  you in?  What's your skype id? (Mine is simonpj0)

simon

|  -----Original Message-----
|  From: ghc-devs [mailto:ghc-devs-bounces at haskell.org] On Behalf Of Dr. ERDI
|  Gergo
|  Sent: 08 August 2013 18:37
|  To: ghc-devs at haskell.org
|  Subject: Instantiating a type with fresh, flexi type variables
|  
|  For my pattern-synonyms branch (see prev. email) I had to write the
|  following function, incl. making TcValidity.fvTypes public:
|  
|  tcInstTypes :: [TcType] -> TcM [TcType]
|  tcInstTypes tys
|     = do { let tvs = fvTypes tys
|          ; (_, _, subst) <- tcInstTyVars tvs
|          ; return $ map (substTy subst) tys }
|  
|  I'm surprised I had to write this myself, and this made me wonder if
|  there's a much better way to handle cases where I have some kind of
|  definition which has some inferred type, and then various use sites
|  of that definition must all have types that can be unified with this
|  original inferred type.
|  Is there?
|  
|  Thanks,
|   	Gergo
|  
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