@neauoire @Screwtapello
yeah, it's a bashism, and it's “basically” syntax sugar for pipes, but very useful especially when you need more than one (I use it often with vimdiff).
For a single one you can *usually* just use a plain pipe if you need a more POSIX-compliant way of doing things, i.e.
curl whatever | left -
*if* the right-hand-side program supports the common convention of indicating standard input with -. Otherwise, /dev/stdin will usually work just as well.