Hypothetical hscript

hello_world.hs

#!/usr/bin/env hsh

-- a. The file name should probably be ".hs", but it's nice to have all the syntax highlitng for free using ".hs".
-- b. it works by having a shell running as a separate process, while the hscript process piping stuff from these quasi-quote
--    template haskell outputs to the shell.
-- c. `hsh` preprocessor reduces some boiler plate, so it is extremely terse to start your helloworld program!
-- d. Otherwise it all looks your regular Haskell program, feel free to add 20+ more GHC extensions.

banner s = "hello world, " <> s

-- using https://hackage.haskell.org/package/PyF
[source|
echo {banner "mister"}
a=41
|]

-- "source" works like bash source, it doesn't create new shell, so variables are shared
[source|
echo "variable is shared: $a"
|]

piped_output.hs

#!/usr/bin/env hsh

substring :: String -> String ->Bool
substring l s = check' l s True where
    check' _ [] h          = True
    check' [] _ h          = False
    check' (x:xs) (y:ys) h = (y == x && check' xs ys False) || (h && check' xs (y:ys) h)

-- | This creates a pair of pipes (stdout, stderr) to the output of `dmesg -w`
[pipe12|
dmesg -w
|] (\(stdout, _) -> go
  -- Only print messages that contains ACPI
  where go = hGetLine stdin >>= (\l -> if substring l "ACPI" then putStrLn l else return ()) >> go
  )

-- | In the same spirit, you may also pipe also the stdin.
[piped0|
-- ... I don't know, think of something
|] (\stdin ->
-- ...
)