I’m trying to fit a simple Student-t model with an `expp1`

prior on \nu. With the following code

```
dat <- tibble(y = rt(n = 100, df = 5))
fit <-
brm(data = dat,
family = student,
formula = y ~ 1,
prior = c(prior(normal(0, 10), class = Intercept),
prior(normal(0, 10), class = sigma),
prior(expp1(1/10), class = nu)))
```

I get this error

Error in stanc(model_code = paste(program, collapse = “\n”), model_name = model_cppname, : failed to parse Stan model ‘file87f99d24c9’ due to the above error.

If I take the \nu prior out, the model runs fine. What am I missing?

Please also provide the following information in addition to your question:

- Operating System: macOS High Sierra
- brms Version: 3.4.0