How to concatename file names in Snakemake? I want to pass a series of files (e.g., a, b) to a program prog like: prog a,b.

Is there a way to do this in Snakemake?

My attempt is:

rule run_prog:
  input: "a", "b"
  output: "output"
  run: "prog {input}"


But the actual command Snakemake generated is prog a b instead of prog a,b.

Any solution to pass a comma concatenated file names to Snakemake?
You can use join to convert the list of input file into a string. 
I think this would work as expected.:

rule run_prog:
    input: "a", "b"
    output: "output"
    run: f"prog {','.join(input)}"