FuncPipelines

Pipelines

The Pipeline api help you define a series of functions that can easily be decomposed and then combined with other function to form a new pipeline. A function (Pipeline) is tagged with one (or multiple) Symbols. The return values of that Pipeline will be bound to those symbols storing in a NamedTuple. Precisely, A Pipeline take two inputs, a regular input value (source) and a NamedTuple (target) that stores the results, applying the function to them, and then store the result with the name it carried with into target. We can then chaining multiple Pipelines into a Pipelines. For example:

julia> pipes = Pipeline{:x}(identity, 1) |> Pipeline{(:sinx, :cosx)}((x,y)->sincos(x))

julia> pipes(0.3)
(x = 0.3, sinx = 0.29552020666133955, cosx = 0.955336489125606)

# define a series of function
julia> pipes = Pipeline{:θ}(Base.Fix1(*, 2), 1) |>
           Pipeline{(:sinθ, :cosθ)}(sincos, :θ) |>
           Pipeline{:tanθ}(2) do target
               target.sinθ / target.cosθ
           end

Pipelines:
  target[θ] := *(2, source)
  target[(sinθ, cosθ)] := sincos(target.θ)
  target[tanθ] := #68(target)

# get the wanted results
julia> pipes2 = pipes |> PipeGet{(:tanθ, :θ)}()
Pipelines:
  target[θ] := *(2, source)
  target[(sinθ, cosθ)] := sincos(target.θ)
  target[tanθ] := #68(target)
  target := (target.tanθ, target.θ)

julia> pipes2(ℯ)
(tanθ = -1.1306063769531505, θ = 5.43656365691809)

# replace some functions in pipeline
julia> pipes3 = pipes2[1] |> Pipeline{:tanθ}(tan, :θ) |> pipes2[end]
Pipelines:
  target[θ] := *(2, source)
  target[tanθ] := tan(target.θ)
  target := (target.tanθ, target.θ)

julia> pipes3(ℯ)
(tanθ = -1.1306063769531507, θ = 5.43656365691809)

# and the pipelines is type stable
julia> using Test; @inferred pipes3(ℯ)
(tanθ = -1.1306063769531507, θ = 5.43656365691809)