[ANN] Armington.jl Constant Elasticity of Substitution aggregators in Julia

Package Announcements
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Hi all,

Announcing Armington.jl, a small package for building and evaluating arbitrarily-nested CES aggregators, trees where each internal node combines its children with a constant elasticity of substitution. See Constant elasticity of substitution - Wikipedia.

Design goals:

  • Zero allocations on evaluation. Tree topology is encoded in the type parameters, so the recursion unrolls at compile time via tuple peeling.
  • AD-friendly. T<:Real throughout, so ForwardDiff duals pass through cleanly.

Quick example:

using Armington

# Two-level Armington: domestic vs. imports (US, EU)
imports = CESNode(4.0, (0.6, 0.4), (CESLeaf(:US), CESLeaf(:EU)); name=:imports)
tree = CESNode(1.5, (0.7, 0.3), (CESLeaf(:dom), imports); name=:total)

leaf_names(tree)            # [:dom, :US, :EU]
aggregate(tree, [10, 5, 8]) # CES composite quantity
show_tree(tree)             # print nesting structure

total: CESNode(σ=1.5, α=(0.7, 0.3))
  └ dom
  └ imports: CESNode(σ=4.0, α=(0.6, 0.4))
    └ US
    └ EU

Repo: GitHub - molivov/Armington.jl: Constant Elasticity of Substitution aggregators in Julia · GitHub

Feedback is welcome.

Cheers

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