--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ext/DiffinitiveSparseArrayKitExt.jl	Sun Jan 12 21:18:44 2025 +0100
@@ -0,0 +1,22 @@
+module DiffinitiveSparseArrayKitExt
+
+using Diffinitive
+using Diffinitive.LazyTensors
+
+using SparseArrayKit
+using Tokens
+
+"""
+    SparseArray(t::LazyTensor)
+
+The sparse tensor representation of `t` with range dimensions to the left and
+domain dimensions to the right. If `L` is a `LazyTensor` with range and
+domain dimension 2 and `v` a 2-tensor, then `A = SparseArray(t)` is
+constructed so that `∑ₖ∑ₗA[i,j,k,l]*v[k,l] == L*v`.
+"""
+function SparseArrayKit.SparseArray(t::LazyTensor)
+    v = ArrayToken(:v, domain_size(t)...)
+    return Tokens._to_tensor(t*v, range_size(t), domain_size(t))
+end
+
+end