From 1a2712ca6c630ebd0f062fa9d1dff38bcb20f968 Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Sat, 11 Jan 2025 19:48:52 -0500
Subject: [PATCH 1/9] Add missing functionality like tagging and priming

---
 src/ITensorBase.jl | 40 +++++++++++++++++++++++++++++++++++++---
 src/quirks.jl      |  4 ++++
 2 files changed, 41 insertions(+), 3 deletions(-)
 create mode 100644 src/quirks.jl

diff --git a/src/ITensorBase.jl b/src/ITensorBase.jl
index f5b931b..62695ee 100644
--- a/src/ITensorBase.jl
+++ b/src/ITensorBase.jl
@@ -1,5 +1,6 @@
 module ITensorBase
 
+using Accessors: @set
 using MapBroadcast: Mapped
 using NamedDimsArrays:
   NamedDimsArrays,
@@ -14,16 +15,29 @@ using NamedDimsArrays:
   name,
   named,
   nameddimsindices,
+  setname,
   unname
 
+const Tag = String
+const TagSet = Set{Tag}
+
+tagset(tags::String) = Set(filter(!isempty, String.(strip.(split(tags, ",")))))
+
 @kwdef struct IndexName <: AbstractName
   id::UInt64 = rand(UInt64)
   plev::Int = 0
-  tags::Set{String} = Set{String}()
-  namedtags::Dict{Symbol,String} = Dict{Symbol,String}()
+  tags::TagSet = TagSet()
 end
 NamedDimsArrays.randname(n::IndexName) = IndexName()
 
+tags(n::IndexName) = n.tags
+settags(n::IndexName, tags) = @set n.tags = tags
+addtags(n::IndexName, ts) = settags(n, tags(n) ∪ tagset(ts))
+
+plev(n::IndexName) = n.plev
+setprime(n::IndexName, plev) = @set n.plev = plev
+prime(n::IndexName) = setprime(n, plev(n) + 1)
+
 struct IndexVal{Value<:Integer} <: AbstractNamedInteger{Value,IndexName}
   value::Value
   name::IndexName
@@ -41,7 +55,15 @@ struct Index{T,Value<:AbstractUnitRange{T}} <: AbstractNamedUnitRange{T,Value,In
   name::IndexName
 end
 
-Index(length::Int) = Index(Base.OneTo(length), IndexName())
+Index(length::Int; kwargs...) = Index(Base.OneTo(length), IndexName(; kwargs...))
+function Index(length::Int, tags::String; kwargs...)
+  return Index(Base.OneTo(length), IndexName(; kwargs..., tags=tagset(tags)))
+end
+
+tags(i::Index) = tags(name(i))
+addtags(i::Index, tags) = setname(i, addtags(name(i), tags))
+prime(i::Index) = setname(i, prime(name(i)))
+Base.adjoint(i::Index) = prime(i)
 
 # Interface
 # TODO: Overload `Base.parent` instead.
@@ -127,9 +149,21 @@ using Accessors: @set
 setdenamed(a::ITensor, denamed) = (@set a.parent = denamed)
 setdenamed!(a::ITensor, denamed) = (a.parent = denamed)
 
+function ITensor(elt::Type, I1::Index, I_rest::Index...)
+  I = (I1, I_rest...)
+  # TODO: Use `FillArrays.Zeros`.
+  return ITensor(zeros(elt, length.(dename.(I))...), I)
+end
+
 function ITensor(I1::Index, I_rest::Index...)
   I = (I1, I_rest...)
   return ITensor(Zeros{UnspecifiedZero}(length.(dename.(I))...), I)
 end
 
+function ITensor()
+  return ITensor(Zeros{UnspecifiedZero}(), ())
+end
+
+include("quirks.jl")
+
 end
diff --git a/src/quirks.jl b/src/quirks.jl
new file mode 100644
index 0000000..1fad08f
--- /dev/null
+++ b/src/quirks.jl
@@ -0,0 +1,4 @@
+# TODO: Define this properly.
+dag(i::Index) = i
+hasqns(i::Index) = false
+dim(i::Index) = length(i)

From bb400c713ebc8c4dd1a3333d338bb35f82e48cb2 Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Sun, 12 Jan 2025 09:40:51 -0500
Subject: [PATCH 2/9] Printing

---
 src/ITensorBase.jl | 54 ++++++++++++++++++++++++++++++++++++++++++++--
 src/quirks.jl      | 10 ++++++++-
 2 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/src/ITensorBase.jl b/src/ITensorBase.jl
index 62695ee..379769b 100644
--- a/src/ITensorBase.jl
+++ b/src/ITensorBase.jl
@@ -23,21 +23,43 @@ const TagSet = Set{Tag}
 
 tagset(tags::String) = Set(filter(!isempty, String.(strip.(split(tags, ",")))))
 
+function tagsstring(tags::TagSet)
+  str = ""
+  length(tags) == 0 && return str
+  tags_vec = collect(tags)
+  for n in 1:(length(tags_vec) - 1)
+    str *= "$(tags_vec[n]),"
+  end
+  str *= "$(tags_vec[end])"
+  return str
+end
+
 @kwdef struct IndexName <: AbstractName
   id::UInt64 = rand(UInt64)
-  plev::Int = 0
   tags::TagSet = TagSet()
+  plev::Int = 0
 end
 NamedDimsArrays.randname(n::IndexName) = IndexName()
 
+id(n::IndexName) = n.id
 tags(n::IndexName) = n.tags
+plev(n::IndexName) = n.plev
+
 settags(n::IndexName, tags) = @set n.tags = tags
 addtags(n::IndexName, ts) = settags(n, tags(n) ∪ tagset(ts))
 
-plev(n::IndexName) = n.plev
 setprime(n::IndexName, plev) = @set n.plev = plev
 prime(n::IndexName) = setprime(n, plev(n) + 1)
 
+function Base.show(io::IO, i::IndexName)
+  idstr = "id=$(id(i) % 1000)"
+  tagsstr = !isempty(tags(i)) ? "|\"$(tagsstring(tags(i)))\"" : ""
+  primestr = primestring(plev(i))
+  str = "IndexName($(idstr)$(tagsstr))$(primestr)"
+  print(io, str)
+  return nothing
+end
+
 struct IndexVal{Value<:Integer} <: AbstractNamedInteger{Value,IndexName}
   value::Value
   name::IndexName
@@ -60,7 +82,12 @@ function Index(length::Int, tags::String; kwargs...)
   return Index(Base.OneTo(length), IndexName(; kwargs..., tags=tagset(tags)))
 end
 
+# TODO: Define for `NamedDimsArrays.NamedViewIndex`.
+id(i::Index) = id(name(i))
 tags(i::Index) = tags(name(i))
+plev(i::Index) = plev(name(i))
+
+# TODO: Define for `NamedDimsArrays.NamedViewIndex`.
 addtags(i::Index, tags) = setname(i, addtags(name(i), tags))
 prime(i::Index) = setname(i, prime(name(i)))
 Base.adjoint(i::Index) = prime(i)
@@ -73,6 +100,29 @@ NamedDimsArrays.name(i::Index) = i.name
 # Constructor
 NamedDimsArrays.named(i::AbstractUnitRange, name::IndexName) = Index(i, name)
 
+function primestring(plev)
+  if plev < 0
+    return " (warning: prime level $plev is less than 0)"
+  end
+  if plev == 0
+    return ""
+  elseif plev > 3
+    return "'$plev"
+  else
+    return "'"^plev
+  end
+end
+
+function Base.show(io::IO, i::Index)
+  lenstr = "length=$(dename(length(i)))"
+  idstr = "|id=$(id(i) % 1000)"
+  tagsstr = !isempty(tags(i)) ? "|\"$(tagsstring(tags(i)))\"" : ""
+  primestr = primestring(plev(i))
+  str = "Index($(lenstr)$(idstr)$(tagsstr))$(primestr)"
+  print(io, str)
+  return nothing
+end
+
 struct NoncontiguousIndex{T,Value<:AbstractVector{T}} <:
        AbstractNamedVector{T,Value,IndexName}
   value::Value
diff --git a/src/quirks.jl b/src/quirks.jl
index 1fad08f..c7b0c2e 100644
--- a/src/quirks.jl
+++ b/src/quirks.jl
@@ -1,4 +1,12 @@
 # TODO: Define this properly.
 dag(i::Index) = i
+# TODO: Deprecate.
+dim(i::Index) = dename(length(i))
+# TODO: Define this properly.
 hasqns(i::Index) = false
-dim(i::Index) = length(i)
+inds(a::ITensor) = nameddimsindices(a)
+# TODO: Deprecate.
+itensor(parent::AbstractArray, nameddimsindices) = ITensor(parent, nameddimsindices)
+function itensor(parent::AbstractArray, i1::Index, i_rest::Index...)
+  return ITensor(parent, (i1, i_rest...))
+end

From 850039095defaf4a2fbfb3ada3c5d3dbf20bb95c Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Wed, 15 Jan 2025 20:42:56 -0500
Subject: [PATCH 3/9] Exports, Broadcast.extrude

---
 src/ITensorBase.jl | 2 ++
 src/quirks.jl      | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/src/ITensorBase.jl b/src/ITensorBase.jl
index 379769b..bf4f8ea 100644
--- a/src/ITensorBase.jl
+++ b/src/ITensorBase.jl
@@ -1,5 +1,7 @@
 module ITensorBase
 
+export ITensor, Index
+
 using Accessors: @set
 using MapBroadcast: Mapped
 using NamedDimsArrays:
diff --git a/src/quirks.jl b/src/quirks.jl
index c7b0c2e..0227d72 100644
--- a/src/quirks.jl
+++ b/src/quirks.jl
@@ -10,3 +10,5 @@ itensor(parent::AbstractArray, nameddimsindices) = ITensor(parent, nameddimsindi
 function itensor(parent::AbstractArray, i1::Index, i_rest::Index...)
   return ITensor(parent, (i1, i_rest...))
 end
+
+Base.Broadcast.extrude(a::AbstractITensor) = a

From e6df7a7798005690b6bf3a8a5a97cf90b88b1c0a Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Thu, 16 Jan 2025 18:35:47 -0500
Subject: [PATCH 4/9] More missing functionality

---
 Project.toml       |  2 ++
 src/ITensorBase.jl | 43 +++++++++++++++++++++++++++++++++++++++----
 src/quirks.jl      | 19 ++++++++++++++++++-
 3 files changed, 59 insertions(+), 5 deletions(-)

diff --git a/Project.toml b/Project.toml
index f6be3a0..e4a6e25 100644
--- a/Project.toml
+++ b/Project.toml
@@ -7,6 +7,7 @@ version = "0.1.2"
 Accessors = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"
 DerivableInterfaces = "6c5e35bf-e59e-4898-b73c-732dcc4ba65f"
 FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"
+LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 MapBroadcast = "ebd9b9da-f48d-417c-9660-449667d60261"
 NamedDimsArrays = "60cbd0c0-df58-4cb7-918c-6f5607b73fde"
 UnallocatedArrays = "43c9e47c-e622-40fb-bf18-a09fc8c466b6"
@@ -16,6 +17,7 @@ UnspecifiedTypes = "42b3faec-625b-4613-8ddc-352bf9672b8d"
 Accessors = "0.1.39"
 DerivableInterfaces = "0.3.7"
 FillArrays = "1.13.0"
+LinearAlgebra = "1.11.0"
 MapBroadcast = "0.1.5"
 NamedDimsArrays = "0.3.0"
 UnallocatedArrays = "0.1.1"
diff --git a/src/ITensorBase.jl b/src/ITensorBase.jl
index bf4f8ea..4ce20aa 100644
--- a/src/ITensorBase.jl
+++ b/src/ITensorBase.jl
@@ -18,6 +18,7 @@ using NamedDimsArrays:
   named,
   nameddimsindices,
   setname,
+  setnameddimsindices,
   unname
 
 const Tag = String
@@ -79,7 +80,9 @@ struct Index{T,Value<:AbstractUnitRange{T}} <: AbstractNamedUnitRange{T,Value,In
   name::IndexName
 end
 
-Index(length::Int; kwargs...) = Index(Base.OneTo(length), IndexName(; kwargs...))
+function Index(length::Int; tags, kwargs...)
+  return Index(Base.OneTo(length), IndexName(; tags=tagset(tags), kwargs...))
+end
 function Index(length::Int, tags::String; kwargs...)
   return Index(Base.OneTo(length), IndexName(; kwargs..., tags=tagset(tags)))
 end
@@ -177,17 +180,30 @@ struct AllocatableArrayInterface <: AbstractAllocatableArrayInterface end
 
 unallocatable(a::AbstractITensor) = NamedDimsArray(a)
 
-@interface ::AbstractAllocatableArrayInterface function Base.setindex!(
-  a::AbstractArray, value, I::Int...
-)
+function setindex_allocatable!(a::AbstractArray, value, I...)
   allocate!(specify_eltype!(a, typeof(value)))
   # TODO: Maybe use `@interface interface(a) a[I...] = value`?
   unallocatable(a)[I...] = value
   return a
 end
 
+# TODO: Combine these by using `Base.to_indices`.
+@interface ::AbstractAllocatableArrayInterface function Base.setindex!(
+  a::AbstractArray, value, I::Int...
+)
+  setindex_allocatable!(a, value, I...)
+  return a
+end
+@interface ::AbstractAllocatableArrayInterface function Base.setindex!(
+  a::AbstractArray, value, I::AbstractNamedInteger...
+)
+  setindex_allocatable!(a, value, I...)
+  return a
+end
+
 @derive AllocatableArrayInterface() (T=AbstractITensor,) begin
   Base.setindex!(::T, ::Any, ::Int...)
+  Base.setindex!(::T, ::Any, ::AbstractNamedInteger...)
 end
 
 mutable struct ITensor <: AbstractITensor
@@ -216,6 +232,25 @@ function ITensor()
   return ITensor(Zeros{UnspecifiedZero}(), ())
 end
 
+inds(a::AbstractITensor) = nameddimsindices(a)
+setinds(a::AbstractITensor, inds) = setnameddimsindices(a, inds)
+
+function uniqueinds(a1::AbstractITensor, a_rest::AbstractITensor...)
+  return setdiff(inds(a1), inds.(a_rest)...)
+end
+function uniqueind(a1::AbstractITensor, a_rest::AbstractITensor...)
+  return only(uniqueinds(a1, a_rest...))
+end
+
+function commoninds(a1::AbstractITensor, a_rest::AbstractITensor...)
+  return intersect(inds(a1), inds.(a_rest)...)
+end
+function commonind(a1::AbstractITensor, a_rest::AbstractITensor...)
+  return only(commoninds(a1, a_rest...))
+end
+
+prime(a::AbstractITensor) = setinds(a, prime.(inds(a)))
+
 include("quirks.jl")
 
 end
diff --git a/src/quirks.jl b/src/quirks.jl
index 0227d72..f9d4e5c 100644
--- a/src/quirks.jl
+++ b/src/quirks.jl
@@ -4,11 +4,28 @@ dag(i::Index) = i
 dim(i::Index) = dename(length(i))
 # TODO: Define this properly.
 hasqns(i::Index) = false
-inds(a::ITensor) = nameddimsindices(a)
 # TODO: Deprecate.
 itensor(parent::AbstractArray, nameddimsindices) = ITensor(parent, nameddimsindices)
 function itensor(parent::AbstractArray, i1::Index, i_rest::Index...)
   return ITensor(parent, (i1, i_rest...))
 end
 
+# This seems to be needed to get broadcasting working.
+# TODO: Investigate this and see if we can get rid of it.
 Base.Broadcast.extrude(a::AbstractITensor) = a
+
+# TODO: Generalize this.
+# Maybe define it as `oneelement`, and base it on
+# `FillArrays.OneElement` (https://juliaarrays.github.io/FillArrays.jl/stable/#FillArrays.OneElement).
+function onehot(iv::Pair{<:Index,<:Int})
+  a = ITensor(first(iv))
+  a[last(iv)] = one(Bool)
+  return a
+end
+
+using LinearAlgebra: svd
+# TODO: Define this in `MatrixAlgebra.jl`/`TensorAlgebra.jl`.
+function factorize(a::AbstractITensor, args...; kwargs...)
+  U, S, V = svd(a, args...; kwargs...)
+  return U, S * V
+end

From 2655456f2ff268e0e45c181c6ed443ebc020ad8c Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Thu, 16 Jan 2025 18:37:03 -0500
Subject: [PATCH 5/9] Add comment

---
 src/ITensorBase.jl | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/ITensorBase.jl b/src/ITensorBase.jl
index 4ce20aa..fd61bc7 100644
--- a/src/ITensorBase.jl
+++ b/src/ITensorBase.jl
@@ -249,6 +249,8 @@ function commonind(a1::AbstractITensor, a_rest::AbstractITensor...)
   return only(commoninds(a1, a_rest...))
 end
 
+# TODO: Use `replaceinds`/`mapinds`, based on
+# `replacenameddimsindices`/`mapnameddimsindices`.
 prime(a::AbstractITensor) = setinds(a, prime.(inds(a)))
 
 include("quirks.jl")

From 24b815a09072bb96f93052916b709516ee090962 Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Thu, 16 Jan 2025 18:38:53 -0500
Subject: [PATCH 6/9] Loosen compat

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index e4a6e25..c34c6e1 100644
--- a/Project.toml
+++ b/Project.toml
@@ -17,7 +17,7 @@ UnspecifiedTypes = "42b3faec-625b-4613-8ddc-352bf9672b8d"
 Accessors = "0.1.39"
 DerivableInterfaces = "0.3.7"
 FillArrays = "1.13.0"
-LinearAlgebra = "1.11.0"
+LinearAlgebra = "1.10"
 MapBroadcast = "0.1.5"
 NamedDimsArrays = "0.3.0"
 UnallocatedArrays = "0.1.1"

From 6c7b1c7282e04782ee018ebcd6a3fdcff58d68b8 Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Thu, 16 Jan 2025 18:39:25 -0500
Subject: [PATCH 7/9] Bump version

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index c34c6e1..09603fd 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "ITensorBase"
 uuid = "4795dd04-0d67-49bb-8f44-b89c448a1dc7"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
-version = "0.1.2"
+version = "0.1.3"
 
 [deps]
 Accessors = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"

From a4b41c5c6664e820dc843ccc49172a98b70ca4d1 Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Thu, 16 Jan 2025 18:42:27 -0500
Subject: [PATCH 8/9] Fix example

---
 examples/README.jl | 3 +--
 src/ITensorBase.jl | 3 ++-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/examples/README.jl b/examples/README.jl
index 48de04f..70c1717 100644
--- a/examples/README.jl
+++ b/examples/README.jl
@@ -20,9 +20,8 @@ julia> Pkg.add("ITensorBase")
 # ## Examples
 
 using ITensorBase: ITensorBase, ITensor, Index
-# TODO: This should be `TensorAlgebra.qr`.
 using LinearAlgebra: qr
-using NamedDimsArrays: NamedDimsArray, aligndims, dimnames, name, unname
+using NamedDimsArrays: aligndims, unname
 using Test: @test
 i = Index(2)
 j = Index(2)
diff --git a/src/ITensorBase.jl b/src/ITensorBase.jl
index fd61bc7..ccecd09 100644
--- a/src/ITensorBase.jl
+++ b/src/ITensorBase.jl
@@ -25,6 +25,7 @@ const Tag = String
 const TagSet = Set{Tag}
 
 tagset(tags::String) = Set(filter(!isempty, String.(strip.(split(tags, ",")))))
+tagset(tags::TagSet) = tags
 
 function tagsstring(tags::TagSet)
   str = ""
@@ -80,7 +81,7 @@ struct Index{T,Value<:AbstractUnitRange{T}} <: AbstractNamedUnitRange{T,Value,In
   name::IndexName
 end
 
-function Index(length::Int; tags, kwargs...)
+function Index(length::Int; tags=TagSet(), kwargs...)
   return Index(Base.OneTo(length), IndexName(; tags=tagset(tags), kwargs...))
 end
 function Index(length::Int, tags::String; kwargs...)

From ac1dbfef220b8849ff8f24a535d63e9399388a20 Mon Sep 17 00:00:00 2001
From: mtfishman <mfishman@flatironinstitute.org>
Date: Thu, 16 Jan 2025 18:43:27 -0500
Subject: [PATCH 9/9] Update README

---
 README.md | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/README.md b/README.md
index a25436a..5216bc7 100644
--- a/README.md
+++ b/README.md
@@ -19,13 +19,8 @@ julia> Pkg.add("ITensorBase")
 
 ````julia
 using ITensorBase: ITensorBase, ITensor, Index
-````
-
-TODO: This should be `TensorAlgebra.qr`.
-
-````julia
 using LinearAlgebra: qr
-using NamedDimsArrays: NamedDimsArray, aligndims, dimnames, name, unname
+using NamedDimsArrays: aligndims, unname
 using Test: @test
 i = Index(2)
 j = Index(2)