3 ms·

I really enjoy using chains of map.filter.foreach.map in scala, it feels powerful but also simple I imagine piping in bash feels similar, so there's at least a

• chandler 9y ago
  > I imagine piping in bash feels similar... It is. Piping is akin to an untyped subset of working with Scala's collections, and there's a similar workflow between the two, e.g.: In bash, you build up a command line with something like (as a stupid example, the number of unique file sizes in a directory): Step 1) $ ls -l Step 2) $ ls -l | awk '{print $5}' Step 3) $ ls -l | awk '/\d+/ {print $5}' Step 4) $ ls -l | awk '/\d+/ {print $5}' | sort -n Step 5) $ ls -l | awk '/\d+/ {print $5}' | sort -n | uniq You can see the correspondence with collections--typically building up in the editor in a similar staged manner ending with something like: Process("ls -l").lines // ls -l part .map(_.split("\\s+")) // awk part { .filter(_.length > 4) // ... .map(_.apply(4).toInt) // } .sorted // sort -n part .distinct // uniq part The tradeoffs between the two are essentially verbosity versus data safety (perhaps not important with a throwaway inspection, but more important when working on larger programs...). However, the building process is the same--you don't write the latter all at once, you gradually mold the pipeline until you get the output you want.
• anko 9y ago
  I am a scala dev but for scripts I use ruby. With pry, I have a great REPL, and ruby has no problem with those filter chains. [1] pry(main)> `ls` => "README.md\n" + "_build\n" + "config\n" + "lib\n" + "mix.exs\n" + "test\n" [2] pry(main)> `ls`.split => ["README.md", "_build", "config", "lib", "mix.exs", "test"] [3] pry(main)> `ls`.split.map(&:upcase) => ["README.MD", "_BUILD", "CONFIG", "LIB", "MIX.EXS", "TEST"] [4] pry(main)> `ls`.split.map(&:upcase).select { |x| x.match(/E/) } => ["README.MD", "MIX.EXS", "TEST"]