DynamicPPL documentation is incorrect

[vboussange]

Minimal working example

using DynamicPPL

# Create the model function.
function gdemo2(model, varinfo, context, x)
    # Assume s² has an InverseGamma distribution.
    s², varinfo = DynamicPPL.tilde_assume!!(
        context, InverseGamma(2, 3), @varname(s²), varinfo
    )

    # Assume m has a Normal distribution.
    m, varinfo = DynamicPPL.tilde_assume!!(
        context, Normal(0, sqrt(s²)), @varname(m), varinfo
    )

    # Observe each value of x[i] according to a Normal distribution.
    for i in eachindex(x)
        _retval, varinfo = DynamicPPL.tilde_observe!!(
            context, Normal(m, sqrt(s²)), x[i], @varname(x[i]), varinfo
        )
    end

    # The final return statement should comprise both the original return
    # value and the updated varinfo.
    return nothing, varinfo
end
gdemo2(x) = DynamicPPL.Model(gdemo2, (; x))

# Instantiate a Model object with our data variables.
model2 = gdemo2([1.5, 2.0])


# Errors
chain = sample(model2, NUTS(), 1000; progress=false)

Description

Hey there, just trying to execute the code provided in https://turinglang.org/docs/developers/compiler/model-manual/ errors.

As a side note, it would be nice to

1. Briefly explain what model is
2. Why do we need to provide a named tuple to DynamicPPL.Model, since gdemo2 is defined with positional arguments?

Julia version info

versioninfo()

(Paste here)

Manifest

]st --manifest

(Paste here)

[penelopeysm]

Hello!

The docs haven't yet been updated for the latest version of Turing (at the top right of the docs page it should say v0.39). The example as shown will still work on Turing 0.39, but if you want to run it on 0.40 you need to do the following

1. remove the context argument from the function definition
2. change context inside the function to model.context

(If you're interested we also described these changes in the DynamicPPL changelog https://github.com/TuringLang/DynamicPPL.jl/blob/main/HISTORY.md#evaluation-contexts.)

I'm going to close this issue because the work on updating the docs for 0.40 is already in progress (TuringLang/docs#636) but please feel free to reopen / ping if there's anything else.