chaining functions with multiple outputs in julia

user_3813428 0
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Julia has good support for chaining functions using |> like

x |> foo |> goo

However for functions with multiple inputs and multiple outputs, this does not work:

julia> f(x, y) = (x+1, y+1)
julia> f(1, 2)
(2, 3)
julia> (1,2) |> f |> f
ERROR: MethodError: no method matching f(::Tuple{Int64,Int64})
Closest candidates are:
  f(::Any, ::Any) at REPL[3]:1
Stacktrace:
[1] |>(::Tuple{Int64,Int64}, ::typeof(f)) at ./operators.jl:813
[2] top-level scope at none:0

We can define f to accept tuple to make it work.

julia> g((x,y)) = (x+1, y+1)
julia> (1,2) |> g |> g
(3, 4)

But the definition of g is not as clear as f. In doc of julia, I've read that functions are calling on tuples, but actually there is differences.

Is there any elegant solution for this?

chain julia tuples function
2 Answers

you could also use splatting operator ... like this:

julia> f(x, y) = (x+1, y+1)
f (generic function with 1 method)

julia> (1,2) |> x->f(x...) |> x->f(x...)
(3, 4)
user_45945320

or you can use an Array

julia> f(x) = [x[1]+1,x[2]+1]
f (generic function with 1 method)

julia> [1,2] |> f |> f
2-element Array{Int64,1}:
 3
 4
user_77769340
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