Re: [Haskell-cafe] TH: quoting name and value

Hi Richard, Thanks for the pointer. It's not exactly what I am after though because I don't need the RHS (AST) of `bar` in my example but the result of running it at compile time. I think it should be simpler than reifying a Name into a TH AST. I will open a new ticket. Thanks, Sylvain On 01/02/2021 18:06, Richard Eisenberg wrote:

Hi Sylvain,

I think you're after https://gitlab.haskell.org/ghc/ghc/-/issues/14474 https://gitlab.haskell.org/ghc/ghc/-/issues/14474. There is some real work to do there, but it should be quite possible.

Richard

...

On Feb 1, 2021, at 4:51 AM, Sylvain Henry mailto:sylvain@haskus.fr> wrote:

Hi,

I have the following kind of template haskell code:

module Foo where foo :: String -> Name -> Q [Dec] foo str name = return []

module Bar where bar :: String bar = "whatever"

module FooBar where import Foo import Bar foo bar 'bar

It works great as in `foo` I can use both bar's Name and bar's value computed at compile time.

But it's unsafe for my purpose because a user could call: `foo "fakeBarValue"  'bar`

So the question is: is there a way to write `foo` so that it can only be used safely?

If not, I guess it could be possible to add a new kind of quote to TH, something like:

data Named a = Named Name a -- constructor not exported so that Named values can't be forged by users.

[namedValue||bar||] :: Named String -- new quote

What do you think?

Thanks, Sylvain

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