some progress

.JuliaFormatter.toml

@@ -0,0 +1 @@
+style = "yas"

.gitignore

@@ -1 +1,2 @@
 /Manifest.toml
+.vscode/

Project.toml

@@ -3,11 +3,25 @@ uuid = "5f87ffc2-9cf1-4a46-8172-465d160bd8cd"
 authors = ["lkdvos <[email protected]> and contributors"]
 version = "1.0.0-DEV"
 
+[deps]
+BlockArrays = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
+LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
+SparseArrayKit = "a9a3c162-d163-4c15-8926-b8794fbefed2"
+Strided = "5e0ebb24-38b0-5f93-81fe-25c709ecae67"
+TensorKit = "07d1fe3e-3e46-537d-9eac-e9e13d0d4cec"
+TensorOperations = "6aa20fa7-93e2-5fca-9bc0-fbd0db3c71a2"
+TestEnv = "1e6cf692-eddd-4d53-88a5-2d735e33781b"
+TupleTools = "9d95972d-f1c8-5527-a6e0-b4b365fa01f6"
+VectorInterface = "409d34a3-91d5-4945-b6ec-7529ddf182d8"
+
 [compat]
 julia = "1"
 
 [extras]
+Combinatorics = "861a8166-3701-5b0c-9a16-15d98fcdc6aa"
+Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+TestExtras = "5ed8adda-3752-4e41-b88a-e8b09835ee3a"
 
 [targets]
-test = ["Test"]
+test = ["Test", "TestExtras", "Random", "Combinatorics"]

src/BlockTensorKit.jl

@@ -1,5 +1,30 @@
 module BlockTensorKit
 
-# Write your package code here.
+using TensorKit
+using SparseArrayKit
+using VectorInterface
+using TensorOperations
+using LinearAlgebra
+using Strided
+using TupleTools: getindices, isperm
+using BlockArrays
+using TupleTools
+
+import VectorInterface
+
+# Spaces
+include("sumspace.jl")
+export SumSpace
+
+# TensorMaps
+include("blockarray.jl")
+include("blocktensor.jl")
+include("sparseblocktensor.jl")
+export BlockTensorMap
+
+# implementations
+include("linalg.jl")
+include("vectorinterface.jl")
+include("tensorinterface.jl")
 
 end

src/blockarray.jl

@@ -0,0 +1,23 @@
+const BlockSparseArray{T, N, A} = BlockArray{T, N, SparseArray{A,N}} where {T, N, A<:AbstractArray{T,N}}
+
+Base.@propagate_inbounds function BlockArrays.viewblock(block_arr::BlockSparseArray{T,N,A},
+                                                        block::Block{N}) where {T,N,A}
+    blks = block.n
+    @boundscheck blockcheckbounds(block_arr, blks...)
+    return get(block_arr.blocks.data, CartesianIndex(blks...)) do 
+        return fill!(similar(A, map(getindex, blocksizes(block_arr), blks)), zero(T))
+    end
+end
+
+Base.:(\)(b1::BlockSparseArray{T,N,A}, b2::BlockSparseArray{T,N,A}) where {T,N,A} = PseudoBlockArray(b1) \ PseudoBlockArray(b2)
+
+function Base.:(/)(b1::BlockSparseArray{T,N,A}, b2::BlockSparseArray{T,N,A}) where {T,N,A}
+    return PseudoBlockArray(b1) / PseudoBlockArray(b2)
+end
+
+# Base.adjoint(A::PseudoBlockArray) = PseudoBlockArray(adjoint(A.blocks), A.axes)
+
+# function LinearAlgebra.ldiv!(A::Adjoint{<:Any,<:Union{LinearAlgebra.QR,LinearAlgebra.QRCompactWY,LinearAlgebra.QRPivoted}},
+#                              B::PseudoBlockMatrix)
+#     return ldiv!(A, B.blocks)
+# end