This looks great!<p>Please consider removing any implicit network calls like the initial "Checking GitHub for updates...". This itself will prevent people from adoption or even trying it any further. This is similar to gnu parallel's --citation, which, albeit a small thing - will scare many people off.<p>Consider adding pivot and unpivot operations. Mlr gets it quite right with syntax, but is unusable since it doesn't work in streaming mode and tries to load everything into memory, despite claiming otherwise.<p>Consider adding basic summing command. Sum is the most common data operation, which could warrant its own special optimized command, instead offloading this to external math processor like lua or python. Even better if this had a group by (-by) and window by (-over) capability. Eg. 'qsv sum col1,col2 -by col3,col4'. Brimdata's zq utility is the only one I know that does this quite right, but is quite clunky to use.<p>Consider adding a laminate command. Essentially adding a new column with a constant. This probably could be achieved by a join with a file with a single row, but why not make this common operation easier to use.<p>Consider the option to concatenate csv files with mismatched headers. cat rows or cat columns complains about the mismatch. One of the most common problems with handling csvs is schema evolution. I and many others would appreciate if we could merge similar csvs together easily.<p>Conversions to and from other standard formats would be appreciated (parquet, ion, fixed width lenghts, avro, etc.). Othe compression formats as well - especially zstd.<p>It would be nice if the tool enabled embedding outputs of external commands easily. Lua and python builtin support is nice, but probably not sufficient. i'd like to be able to run a jq command on a single column and merge it back as another for example.<p>Inspiration:<p><pre><code> - csvquote: https://news.ycombinator.com/item?id=31351393
- teip: https://github.com/greymd/teip</code></pre>
related: <a href="https://github.com/johnkerl/miller">https://github.com/johnkerl/miller</a><p>I am wondering who really uses these tools and for what since there are R and python data science tools available?
An incomplete list of other similar tools: <a href="https://github.com/dkogan/vnlog/#description">https://github.com/dkogan/vnlog/#description</a>