Hi Simon, I don't think I need to construct dictionaries for new Typeable instances. I only need to find and assemble *existing* Typeable instances into combinations like Typeable [(Bool,Int -> String)], and I don't know how to do so in a GHC plug-in. Pointers greatly appreciated!
-- Conal On Tue, Nov 5, 2013 at 1:13 AM, Simon Peyton-Jones <[email protected]>wrote: > I’m not sure what you mean by “synthesise”. > > > > Typeable instances can no longer be hand-written; they must be derived by > GHC. That’s to keep them type-secure. > > > > A core-level plug-in can’t generate fresh instances. There are some new > plug-in hooks that fit earlier in the pipeline, which can. Maybe you can > use that, and generate a data type decl with “deriving Typeable”? > > > Simon > > > > *From:* ghc-devs [mailto:[email protected]] *On Behalf Of *Conal > Elliott > *Sent:* 04 November 2013 20:08 > *To:* [email protected] > *Subject:* Finding & assembling class dictionaries from GHC plugins? > > > > I'm working on a GHC plugin (for compiling Haskell to hardware), and I > need to synthesize Typeable (and maybe other) class dictionaries for a wide > range of types, including composite types (functions, pairs, lists, etc). > Can it be done, and how? I think I'm mainly looking for mechanics of > finding existing class instances (however they're defined) and assembling > them (for parametrized/composite dictionaries), rather than mechanisms > specific to Typeable. > > Thanks, -- Conal >
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