diff --git a/Project.toml b/Project.toml
index 4abd2fa..485ab2e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "ConstraintDomains"
 uuid = "5800fd60-8556-4464-8d61-84ebf7a0bedb"
 authors = ["Jean-François Baffier"]
-version = "0.3.15"
+version = "0.4.0"
 
 [deps]
 ConstraintCommons = "e37357d9-0691-492f-a822-e5ea6a920954"
@@ -11,7 +11,7 @@ StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 TestItems = "1c621080-faea-4a02-84b6-bbd5e436b8fe"
 
 [compat]
-ConstraintCommons = "0.2"
+ConstraintCommons = "0.3"
 Intervals = "1"
 PatternFolds = "0.2"
 StatsBase = "0.34"
diff --git a/src/common.jl b/src/common.jl
index 93e68a9..15dfecd 100644
--- a/src/common.jl
+++ b/src/common.jl
@@ -64,7 +64,7 @@ Convert various arguments into valid domains format.
 to_domains(domain_sizes::Vector{Int}) = map(ds -> domain(0:ds), domain_sizes)
 
 function to_domains(X, ds::Int = δ_extrema(X) + 1)
-    d = domain(0:ds-1)
+    d = domain(0:(ds-1))
     return fill(d, length(first(X)))
 end
 
diff --git a/src/explore.jl b/src/explore.jl
index 6c93895..8a0db35 100644
--- a/src/explore.jl
+++ b/src/explore.jl
@@ -1,4 +1,4 @@
-struct ExploreSettings
+mutable struct ExploreSettings
     complete_search_limit::Int
     max_samplings::Int
     search::Symbol
@@ -42,22 +42,52 @@ function ExploreSettings(
     return ExploreSettings(complete_search_limit, max_samplings, search, solutions_limit)
 end
 
-struct ExplorerState{T}
+abstract type AbstractExplorerState end
+
+struct CompleteExplorerState{N,T} <: AbstractExplorerState
+    best::Vector{T}
+    solutions::Vector{NTuple{N,T}}
+    non_solutions::Vector{NTuple{N,T}}
+
+    CompleteExplorerState{N,T}() where {N,T} =
+        new{N,T}(Vector{T}(), Vector{NTuple{N,T}}(), Vector{NTuple{N,T}}())
+end
+
+function explorer_state(domains, ::Val{:complete})
+    return CompleteExplorerState{length(domains),Union{map(eltype, domains)...}}()
+end
+
+struct PartialExplorerState{T} <: AbstractExplorerState
     best::Vector{T}
     solutions::Set{Vector{T}}
     non_solutions::Set{Vector{T}}
 
-    ExplorerState{T}() where {T} = new{T}([], Set{Vector{T}}(), Set{Vector{T}}())
+    PartialExplorerState{T}() where {T} =
+        new{T}(Vector{T}(), Set{Vector{T}}(), Set{Vector{T}}())
+end
+function explorer_state(domains, ::Val{:partial})
+    return PartialExplorerState{Union{map(eltype, domains)...}}()
 end
 
-ExplorerState(domains) = ExplorerState{Union{map(eltype, domains)...}}()
-
-mutable struct Explorer{F1<:Function,D<:AbstractDomain,F2<:Union{Function,Nothing},T}
+mutable struct Explorer{
+    F1<:Function,
+    D<:AbstractDomain,
+    F2<:Union{Function,Nothing},
+    S<:AbstractExplorerState,
+}
     concepts::Dict{Int,Tuple{F1,Vector{Int}}}
     domains::Dict{Int,D}
     objective::F2
     settings::ExploreSettings
-    state::ExplorerState{T}
+    state::S
+
+    function Explorer(concepts, domains, objective, settings, state)
+        F1 = isempty(concepts) ? Function : typeof(concepts).parameters[2].parameters[1]
+        D = isempty(domains) ? AbstractDomain : typeof(domains).parameters[2]
+        F2 = typeof(objective)
+        S = typeof(state)
+        return new{F1,D,F2,S}(concepts, domains, objective, settings, state)
+    end
 end
 
 """
@@ -88,13 +118,14 @@ function Explorer(
     objective = nothing;
     settings = ExploreSettings(domains),
 )
-    F1 = isempty(concepts) ? Function : Union{map(c -> typeof(c[1]), concepts)...}
-    D = isempty(domains) ? AbstractDomain : Union{map(typeof, domains)...}
-    F2 = typeof(objective)
-    T = isempty(domains) ? Real : Union{map(eltype, domains)...}
+    if settings.search == :flexible
+        settings.search =
+            settings.max_samplings < settings.complete_search_limit ? :complete : :partial
+    end
+    state = explorer_state(domains, Val(settings.search))
     d_c = Dict(enumerate(concepts))
     d_d = Dict(enumerate(domains))
-    return Explorer{F1,D,F2,T}(d_c, d_d, objective, settings, ExplorerState{T}())
+    return Explorer(d_c, d_d, objective, settings, state)
 end
 
 function Explorer()
@@ -225,15 +256,14 @@ function update_exploration!(explorer, f, c, search = explorer.settings.search)
     obj = explorer.objective
     sl = search == :complete ? Inf : explorer.settings.solutions_limit
 
-    cv = collect(c)
-    if f(cv)
+    if f(c)
         if length(solutions) < sl
-            push!(solutions, cv)
+            push!(solutions, c)
             obj !== nothing && (explorer.state.best = argmin(obj, solutions))
         end
     else
         if length(non_sltns) < sl
-            push!(non_sltns, cv)
+            push!(non_sltns, c)
         end
     end
     return nothing
@@ -261,7 +291,9 @@ function _explore!(explorer, f, ::Val{:partial};)
 end
 
 function _explore!(explorer, f, ::Val{:complete})
-    C = Base.Iterators.product(map(d -> get_domain(d), explorer.domains |> values)...)
+    C = Base.Iterators.product(
+        Iterators.map(d -> get_domain(d), explorer.domains |> values)...,
+    )
     foreach(c -> update_exploration!(explorer, f, c, :complete), C)
     return nothing
 end
@@ -293,12 +325,7 @@ function explore!(explorer::Explorer)
             f(isempty(vars) ? x : @view x[vars]) for
             (f, vars) in explorer.concepts |> values
         ])
-    s = explorer.settings
-    search = s.search
-    if search == :flexible
-        search = s.max_samplings < s.complete_search_limit ? :complete : :partial
-    end
-    return _explore!(explorer, c, Val(search))
+    return _explore!(explorer, c, Val(explorer.settings.search))
 end
 
 
@@ -346,5 +373,5 @@ end
     @test length(X) == factorial(4)
     @test length(X̅) == 4^4 - factorial(4)
 
-    explorer = ConstraintDomains.Explorer()
+    explorer = ConstraintDomains.Explorer([(allunique, 1:4)], domains)
 end