diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index fc1526b..6a79e34 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -10,7 +10,7 @@ jobs:
       fail-fast: false
       matrix:
         version:
-          - "^1.6.0-0"
+          - "^1.7.0-0"
           - 'nightly'
         os:
           - ubuntu-latest
diff --git a/Project.toml b/Project.toml
index 722e0f6..c41fce8 100644
--- a/Project.toml
+++ b/Project.toml
@@ -8,7 +8,7 @@ Lazy = "50d2b5c4-7a5e-59d5-8109-a42b560f39c0"
 
 [compat]
 Lazy = "0.15"
-julia = "1.6"
+julia = "1.7"
 
 [extras]
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
diff --git a/src/PatternFolds.jl b/src/PatternFolds.jl
index 1c8bbbb..c0af992 100644
--- a/src/PatternFolds.jl
+++ b/src/PatternFolds.jl
@@ -4,19 +4,31 @@ module PatternFolds
 using Lazy
 
 # exports
-export PatternFold
-export IVectorFold, VectorFold
-export Interval, IntervalsFold
-export pattern, gap, folds, check_pattern
+export Interval
+export IntervalsFold
+export IVectorFold
+export VectorFold
+
+export a_isless
+export a_ismore
+export b_isless
+export b_ismore
+export check_pattern
+export closed
+export fold
+export folds
+export gap
 export length
-export fold, unfold
-export value, closed, opened
-export a_isless, b_isless, a_ismore, b_ismore
+export make_vector_fold
+export opened
+export pattern
+export unfold
+export value
 
 # includes
+include("intervals.jl")
 include("common.jl")
 include("immutable_vector.jl")
 include("vector.jl")
-include("intervals.jl")
 
 end
diff --git a/src/common.jl b/src/common.jl
index e78d3fc..01c5b07 100644
--- a/src/common.jl
+++ b/src/common.jl
@@ -1,12 +1,26 @@
 """
-    PatternFold{T, P}
-An abstract stype used as an interface for folded patterns such as `VectorFold`.
+    AbstractVectorFold{T, P}
+An abstract type used as an interface for folded vectors such as `VectorFold`.
 To implement the interface and inherit from it, a new structure must define three fields:
 - `pattern::P`. Note that both `length(::P)` and `rand(::P)` methods must be available
 - `gap::T`
 - `folds::int`
 """
-abstract type PatternFold{T, P} end
+abstract type AbstractVectorFold{T} <: AbstractVector{T} end
+
+"""
+    PatternFold{T, P}
+A `Union` type used as an interface for folded patterns such as `VectorFold`.
+To implement the interface and inherit from it, a new structure `MyFold{T[,P]}` must define three fields:
+- `pattern::P`. Note that both `length(::P)` and `rand(::P)` methods must be available
+- `gap::T`S
+- `folds::int`
+Finally one can redefine PatternFold{T}
+```julia
+PatternFold{T} = Union{AbstractVectorFold{T}, IntervalsFold{T}, MyFold{T[,P]}}
+```
+"""
+PatternFold{T} = Union{AbstractVectorFold{T}, IntervalsFold{T}}
 
 """
     pattern(<:PatternFold)
@@ -29,7 +43,6 @@ folds(pf) = pf.folds
 # Forwards isempty, ndims
 @forward PatternFold.pattern Base.isempty, Base.ndims
 
-# TODO - look if another name is more appropriate
 """
     pattern_length(pf<:PatternFold)
 Return the length of the basic pattern of `pf`.
@@ -41,11 +54,12 @@ pattern_length(pf) = length(pattern(pf))
 Return the length of `pf` if unfolded.
 """
 Base.length(pf::PatternFold) = pattern_length(pf) * folds(pf)
+Base.size(pf::PatternFold) = (length(pf),)
 
 """
     eltype(pf<: PatternFolds)
 """
-Base.eltype(::Type{<:PatternFold{T,P}}) where {T,P} = T
+Base.eltype(::Type{<:PatternFold{T}}) where {T} = T
 
 """
     rand(pf<:PatternFold)
@@ -83,6 +97,14 @@ function fold(v::V, depth = 0; kind = :mutable) where {T <: Real, V <: AbstractV
     end
 end
 
+"""
+    make_vector_fold(pattern, gap, fold, kind = :mutable)
+A dispatcher to construct a folded vector. The `kind` of vector can be set to either `:mutable` (default) or `:immutable`. The default is faster in most cases but it depends on the `pattern`, `gap`, and `fold` parameters. For critical code, it is recommended to benchmark both options.
+"""
 function make_vector_fold(pattern, gap, fold, kind = :mutable)
     return make_vector_fold(pattern, gap, fold, Val(kind))
 end
+
+function Base.print_array(io::IO, X::AbstractVectorFold)
+    print(io, "\tPattern: $(pattern(X))\n\tGap: $(gap(X))\n\tFolds: $(folds(X))")
+end
diff --git a/src/immutable_vector.jl b/src/immutable_vector.jl
index c96ce49..2774519 100644
--- a/src/immutable_vector.jl
+++ b/src/immutable_vector.jl
@@ -2,7 +2,7 @@
     VectorFold{T,V <: AbstractVector{T}}
 A folded vector structure that extends the methods of AbstractVector to a folded structure.
 """
-struct IVectorFold{T,V <: AbstractVector{T}} <: PatternFold{T,V}
+struct IVectorFold{T,V <: AbstractVector{T}} <: AbstractVectorFold{T}
     pattern::V
     gap::T
     folds::Int
diff --git a/src/intervals.jl b/src/intervals.jl
index a857ae1..ad028cf 100644
--- a/src/intervals.jl
+++ b/src/intervals.jl
@@ -52,7 +52,7 @@ Base.isempty(i::Interval) = size(i) == 0 && (opened(i, :a) || opened(i, :b))
 Base.ndims(::Interval) = 1
 Base.rand(i::Interval) = rand() * size(i) + value(i, :a)
 
-mutable struct IntervalsFold{T <: Real} <: PatternFold{T, Interval{T}}
+mutable struct IntervalsFold{T <: Real} #<: PatternFold{T, Interval{T}}
     pattern::Interval{T}
     gap::T
     folds::Int
diff --git a/src/vector.jl b/src/vector.jl
index 9dd563d..291746f 100644
--- a/src/vector.jl
+++ b/src/vector.jl
@@ -1,9 +1,9 @@
 """
-    MVectorFold{T,V <: AbstractVector{T}}
-A mutable structure for folded vector that extends the methods of AbstractVector. Compared to `VectorFold`, this tructure is about 20% faster using iterators. Unfolding is twice slower though.
-Note that this structure keep an active pointer to the `current` *unfolded* pattern. However, its external behavior is similar to `VectorFold`.
+    VectorFold{T,V <: AbstractVector{T}}
+A mutable structure for folded vector that extends the methods of AbstractVector. Compared to `IVectorFold`, this tructure is about 20% faster using iterators.
+Note that this structure keep an active pointer to the `current` *unfolded* pattern. However, its external behavior is similar to `IVectorFold`.
 """
-mutable struct VectorFold{T,V <: AbstractVector{T}} <: PatternFold{T,V}
+mutable struct VectorFold{T,V <: AbstractVector{T}} <: AbstractVectorFold{T}
     pattern::V
     gap::T
     folds::Int
@@ -22,7 +22,7 @@ end
 pattern(mvf::VectorFold, index) = pattern(mvf)[index]
 
 """
-    set_fold!(mvf::MVectorFold, new_fold = mvf.current + 1)
+    set_fold!(mvf::VectorFold, new_fold = mvf.current + 1)
 Set the *unfolded* pattern to `new_fold`. By default move the next *fold* after `current`.
 """
 function set_fold!(mvf, new_fold = mvf.current + 1)
diff --git a/test/vector.jl b/test/vector.jl
index 6a3991a..461c96e 100644
--- a/test/vector.jl
+++ b/test/vector.jl
@@ -1,6 +1,6 @@
 @testset "VectorFold" begin
     vf_dict = Dict([
-        IVectorFold([1,2], 10, 5) => Dict(
+        make_vector_fold([1,2], 10, 5, :immutable) => Dict(
             :pattern => [1,2],
             :gap => 10,
             :folds => 5,
@@ -8,7 +8,7 @@
             :unfold => [1,2,11,12,21,22,31,32,41,42],
             :reverse => reverse([1,2,11,12,21,22,31,32,41,42]),
         ),
-        VectorFold([1,2], 10, 5) => Dict(
+        make_vector_fold([1,2], 10, 5, :mutable) => Dict(
             :pattern => [1,2],
             :gap => 10,
             :folds => 5,
@@ -29,16 +29,16 @@
         @test collect(vf) == [i for i in vf] == unfold(vf)
         @test collect(Iterators.reverse(vf)) == reverse(collect(vf)) == results[:reverse]
     end
-    @test isempty(IVectorFold(Vector(),1,1))
-    @test isempty(VectorFold(Vector(),1,1))
+    @test isempty(make_vector_fold(Vector(),1,1,:immutable))
+    @test isempty(make_vector_fold(Vector(),1,1))
 
-    v1 = VectorFold([42,3,45,6],13,4)
+    v1 = make_vector_fold([42,3,45,6],13,4)
     w1 = unfold(v1)
     v11 = fold(w1)
 
     @test unfold(v11) == w1
 
-    v2 = VectorFold([34,34,43,43],10,3)
+    v2 = make_vector_fold([34,34,43,43],10,3)
     w2 = unfold(v2)
     v22 = fold(w2)