One of the things I love about programming in dialects of ML like ocaml and f# is the forward pipe operator:

  x
  |> f
  |> g
  |> h

It's nice because it just puts whatever's on the left of the operator in as the last argument. So it also works for functions with an arity of more than one.

So if it were something like

  h(z, g(y, f(x))

you can write it as

  x
  |> f
  |> g y
  |> h z

It works really nicely for data munging code:

  my_data
  |> filter (x => x > 37)
  |> select (x => x * 2)
  |> sum

but unlike doing it with method calls in object oriented code, inserting a new function into the chain doesn't involve modifying a class or or mucking around with more complex language features like extension methods and traits.

▲ pfdietz 2 hours ago | parent [-]

Lisp macros let you do similar things, and you don't have to change the language itself.

	▲	tomsmeding 2 hours ago \| parent \| next [-]
		In ML family languages you also don't have to change the language for this, as function application is naturally "argument-by-argument" (the term is "curried"): the syntax is normally f x y z but (f x y) z and (((f)) (x)) y z are just as valid, and indeed f x y will be a function taking one argument. Thus \|> can just take a function of one argument and be done.
	▲	bunderbunder 2 hours ago \| parent \| prev [-]
		Maybe I've just been doing too much Racket lately and that's affecting how I view things, but it's real hard for me to not think of lisp macros as a mechanism for changing the language itself. Especially if it's something like a reader macro.