Hi ghc-devs,
About 10 days ago, I made a thread about defining a function called
elaborateExpr which turns a string into a core expression
<https://github.com/yiyunliu/ghc-elaboration-test/blob/8f362ad92dc6601b4cb7e4c76f0a42bc6b64480f/src/Main.hs#L55>
within an interactive context. Now here's an unexpected behavior which
I'm not sure how to deal with.
Given the expression:
(\x -> x + 1) :: Int -> Int
I expect to get something that looks like:
\ (x :: Int) -> + @ Int GHC.Num.$fNumInt x (GHC.Types.I# 1#)
where GHC.Num.$fNumInt is the exported dictionary.
What I actually get is something like this:
\ (x :: Int) -> + @ Int $dNum_someuniqueid x (GHC.Types.I# 1#)
where $dNum_someuniqueid is a free dictionary variable within the
expression.
I was confused by the occurrence of the free variable $dNum at first,
but after running the command: "ghc -ddump-ds-preopt somefile.hs" to
dump the core bindings, I found that the dictionary variables like
$dNum_ are actually local variables defined at the top-level.
My objective is to inline those top-level dictionary definitions into
the core expression using let bindings, but it seems tricky since I'm
doing everything within an interactive context. Calling getBindings
<https://hackage.haskell.org/package/ghc-8.6.5/docs/GHC.html#v:getBindings>
only gives me the expression I elaborated, but the dictionary is no
where to be found.
Interestingly, when I turn on flags such as "DeferTypedHoles" or
"DeferOutOfScopeVariables", all the dictionaries are defined locally in
let bindings. However, I can't replicate that behavior even with the
flags on in the interactive context. How do I find the dictionaries?
Thanks,
- Yiyun
_______________________________________________
ghc-devs mailing list
[email protected]
http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs
