[R] printing a data.frame that contains a list-column of S4 objects

Is there a general problem with printing a data.frame when it has a list-column of S4 objects? Or am I just unlucky in my life choices? I ran across this with objects from the git2r package but maintainer Stefan Widgren points out this example below from Matrix as well. I note that the offending

[R] recursive function, how to avoid list structure in return value

. Can anyone show me show? Thanks, Jenny Bryan Demo of my problem -- (Note: although my question has nothing to do with hierarchical clustering per se, my example does assume knowledge of the 'merge' object.) ## faking the key aspects of an hclust object myClust - list(merge = rbind(c(-1