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munchler • today at 2:41 PM • 3 replies • view on HN

Well, I totally disagree with this. One of the main benefits of currying is the ability to chain function calls together. For example, in F# this is typically done with the |> operator:

    let result =
        input
            |> foobinade a b
            |> barbalyze c d
Or, if we really want to name our partial function before applying it, we can use the >> operator instead:

    let f = foobinade a b >> barbalyze c d
    let result = f input
Requiring an explicit "hole" for this defeats the purpose:

    let f = barbalyze(c, d, foobinade(a, b, $))
    let result = f(input)
Or, just as bad, you could give up on partial function application entirely and go with:

    let result = barbalyze(c, d, foobinade(a, b, input))
Either way, I hope that gives everyone the same "ick" it gives me.

Replies

emih • today at 2:47 PM

You can still do this though:

  let result = (barbalyze(c, d, $) . foobinade(a, b, $)) input
Or if you prefer left-to-right:

  let result = input
    |> foobinade(a, b, $)
    |> barbalyze(c, d, $)
Maybe what isn't clear is that this hole operator would bind to the innermost function call, not the whole statement.
➕ show 3 replies
skybrian • today at 2:58 PM

For pipelines in any language, putting one function call per line often works well. Naming the variables can help readability. It also makes using a debugger easier:

  let foos = foobinate(a, b, input)
  let bars = barbakize(c, d, foos)
Other languages have method call syntax, which allows some chaining in a way that works well with autocomplete.
➕ show 1 reply