Is there a way to print progress from within a chunk when rendering?

[venpopov]

Description

Suppose I have a document in which one R chunk might take a long time to compute. For example:

#| label: param-recovery-bayes
recovery_est_bayes <- with_cache(
  "output/algo5_recovery_bayes.rds",
  purrr::pmap_dfr(recovery_true, fit_one_bayes, .progress = TRUE)
)

When I run it interactively, purrr prints a progress bar to the R console. Is there some setting or another way to output progress information, so that when I render the document with Quarto, I get some progress output in the terminal? Currently it shows the names of the chunks, which is useful as within-document progress, but that's not that useful when one chunk takes much longer:

processing file: diagnostics-algo5-bayes.qmd
1/31                            
2/31 [setup]                    
3/31                            
4/31 [define-family-stanvars]   
5/31                            
6/31 [define-priors]            
7/31                            
8/31 [simulate-data]            
9/31                            
10/31 [fit-sim]                  
11/31                            
12/31 [fit-summary]              
13/31                            
14/31 [fit-plot]                 
15/31                            
16/31 [compare-params]           
17/31                            
18/31 [pp-arc-trajectories]      
19/31                            
20/31 [param-recovery-bayes]  

I could try to write some progress information to a temporary log file, but I wonder if there is a more direct way to output chunk information to the terminal within the output that quarto generates above.

[mcanouil]

The progress you see is from knitr.
You can provide to knitr a custom function, via knitr.progress.fun (see https://yihui.org/knitr/options/).
Several R packages offer functions for knitr.

[venpopov]

thanks, that's a good pointer to dig deeper