add basic fallbacks

src/Groups.jl

@@ -14,25 +14,9 @@ using LinearAlgebra
 using Markdown
 
 
-Base.one(G::Generic.PermGroup) = Generic.Perm(G.n)
-Base.one(r::NCRingElem) = one(parent(r))
-
-###############################################################################
-#
-#   ParentType / ObjectType definition
-#
-
 include("types.jl")
 include("gsymbols.jl")
-
-function Base.one(G::Gr) where Gr <: AbstractFPGroup
-    El = elem_type(G)
-    id = El(eltype(El)[])
-    id.parent = G
-    return id
-end
-
-elem_type(G::Gr) where Gr <:AbstractFPGroup = elem_type(Gr) # fallback definition
+include("fallbacks.jl")
 
 @doc doc"""
 

src/fallbacks.jl

@@ -0,0 +1,17 @@
+# workarounds
+Base.one(G::Generic.PermGroup) = Generic.Perm(G.n)
+Base.one(r::NCRingElem) = one(parent(r))
+
+# fallback definitions
+# note: the user should implement those on type, when possible
+Base.eltype(w::GW) where GW<:GWord = eltype(GW)
+AbstractAlgebra.elem_type(G::Gr) where Gr <:AbstractFPGroup = elem_type(Gr)
+
+AbstractAlgebra.parent_type(g::Gw) where Gw <:GWord = parent_type(parent(Gr))
+
+function Base.one(G::Gr) where Gr <: AbstractFPGroup
+    El = elem_type(G)
+    id = El(eltype(El)[])
+    id.parent = G
+    return id
+end