diff --git a/Project.toml b/Project.toml
index 18de09b..829f113 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,16 +1,16 @@
 name = "HerbConstraints"
 uuid = "1fa96474-3206-4513-b4fa-23913f296dfc"
 authors = ["Jaap de Jong <jaapdejong15@gmail.com>"]
-version = "0.1.0"
+version = "0.1.1"
 
 [deps]
 HerbGrammar = "4ef9e186-2fe5-4b24-8de7-9f7291f24af7"
 HerbCore = "2b23ba43-8213-43cb-b5ea-38c12b45bd45"
 
 [compat]
-julia = "1.8"
-HerbCore = "0.1.0"
-HerbGrammar = "0.1.0"
+HerbCore = "^0.2.0"
+HerbGrammar = "^0.2.0"
+julia = "^1.8"
 
 [extras]
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
diff --git a/README.md b/README.md
index 00a87e2..50f8a55 100644
--- a/README.md
+++ b/README.md
@@ -1,10 +1,10 @@
 # HerbConstraints.jl
 
+
+[![Build Status](https://github.com/Herb-AI/HerbConstraints.jl/actions/workflows/CI.yml/badge.svg?branch=master)](https://github.com/Herb-AI/HerbConstraints.jl/actions/workflows/CI.yml?query=branch%3Amaster)
+
 This package contains the functionality to formulate, represent and use constraints within `Herb`. 
 
 Constraints are formulated as context-sensitive grammars. Further, they are divided into global and local constraints, that may be partially mapped to each other. 
 
 `HerbConstraints.jl` provides functionality to propagate constraints and match constraint patterns efficiently. Further, provides error handling through `matchfail` and `matchnode`.
-
-[![Build Status](https://github.com/Herb-AI/HerbConstraints.jl/actions/workflows/CI.yml/badge.svg?branch=master)](https://github.com/Herb-AI/HerbConstraints.jl/actions/workflows/CI.yml?query=branch%3Amaster)
-
diff --git a/src/HerbConstraints.jl b/src/HerbConstraints.jl
index 06827c9..38fc29d 100644
--- a/src/HerbConstraints.jl
+++ b/src/HerbConstraints.jl
@@ -10,7 +10,7 @@ Abstract type representing all propagator constraints.
 Each propagator constraint has an implementation of a [`propagate`](@ref)-function that takes
 
 - the [`PropagatorConstraint`](@ref)
-- a [`Grammar`](@ref)
+- a [`AbstractGrammar`](@ref)
 - a [`GrammarContext`](@ref), which most importantly contains the tree and the location 
   in the tree where propagation should take place.
 - The `domain` which the [`propagate`](@ref)-function prunes. 
@@ -31,7 +31,7 @@ Each local constraint contains a `path` to a specific location in the tree.
 Each local constraint has an implementation of a [`propagate`](@ref)-function that takes
 
 - the [`LocalConstraint`](@ref)
-- a [`Grammar`](@ref)
+- a [`AbstractGrammar`](@ref)
 - a [`GrammarContext`](@ref), which most importantly contains the tree and the location 
   in the tree where propagation should take place.
 - The `domain` which the [`propagate`](@ref)-function prunes. 
diff --git a/src/localconstraints/local_condition.jl b/src/localconstraints/local_condition.jl
index 99af0a0..26faf4a 100644
--- a/src/localconstraints/local_condition.jl
+++ b/src/localconstraints/local_condition.jl
@@ -1,12 +1,29 @@
+"""
+    LocalCondition <: LocalConstraint
+
+Forbids any subtree that matches the pattern defined by `tree` and where the 
+[`RuleNode`](@ref) that is matched to the variable in the pattern violates the 
+predicate given by the `condition` function.
+    
+The `condition` function takes a `RuleNode` tree and should return a `Bool`.
+    
+This constraint is only enforced at the location defined by `path`.
+Use a `Condition` constraint for enforcing this throughout the entire search space.
+"""
 mutable struct LocalCondition <: LocalConstraint
     path::Vector{Int}
     tree::AbstractMatchNode
     condition::Function
 end
 
+"""
+    propagate(c::LocalCondition, ::AbstractGrammar, context::GrammarContext, domain::Vector{Int}, filled_hole::Union{HoleReference, Nothing})
+
+Propagates the [`LocalCondition`](@ref) constraint.
+"""
 function propagate(
     c::LocalCondition, 
-    ::Grammar, 
+    ::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
diff --git a/src/localconstraints/local_forbidden.jl b/src/localconstraints/local_forbidden.jl
index 821cb68..2d78909 100644
--- a/src/localconstraints/local_forbidden.jl
+++ b/src/localconstraints/local_forbidden.jl
@@ -18,7 +18,7 @@ the RuleNode at the given path match the pattern defined by the MatchNode.
 """
 function propagate(
     c::LocalForbidden, 
-    ::Grammar, 
+    ::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
diff --git a/src/localconstraints/local_one_of.jl b/src/localconstraints/local_one_of.jl
index cb6624f..89c8564 100644
--- a/src/localconstraints/local_one_of.jl
+++ b/src/localconstraints/local_one_of.jl
@@ -13,7 +13,7 @@ It enforces that at least one of its given constraints hold.
 """
 function propagate(
     c::LocalOneOf, 
-    g::Grammar, 
+    g::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int},
     filled_hole::Union{HoleReference, Nothing}
diff --git a/src/localconstraints/local_ordered.jl b/src/localconstraints/local_ordered.jl
index 39d1aac..ff2d985 100644
--- a/src/localconstraints/local_ordered.jl
+++ b/src/localconstraints/local_ordered.jl
@@ -16,7 +16,7 @@ constraint.
 """
 function propagate(
     c::LocalOrdered, 
-    ::Grammar, 
+    ::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
diff --git a/src/matchnode.jl b/src/matchnode.jl
index e6551ab..c3a693a 100644
--- a/src/matchnode.jl
+++ b/src/matchnode.jl
@@ -78,12 +78,12 @@ contains_var(mn::MatchNode, var::Symbol) = any(contains_var(c, var) for c ∈ mn
 
 
 """
-    matchnode2expr(pattern::MatchNode, grammar::Grammar)
+    matchnode2expr(pattern::MatchNode, grammar::AbstractGrammar)
 
 Converts a MatchNode tree into a Julia expression. 
 This is primarily useful for pretty-printing a pattern. Returns the corresponding expression.
 """
-function matchnode2expr(pattern::MatchNode, grammar::Grammar)
+function matchnode2expr(pattern::MatchNode, grammar::AbstractGrammar)
 	root = deepcopy(grammar.rules[pattern.rule_ind])
 	if !grammar.isterminal[pattern.rule_ind] # not terminal
 		root,_ = _matchnode2expr(root, pattern, grammar)
@@ -92,21 +92,21 @@ function matchnode2expr(pattern::MatchNode, grammar::Grammar)
 end
 
 """
-    matchnode2expr(pattern::MatchVar, grammar::Grammar)
+    matchnode2expr(pattern::MatchVar, grammar::AbstractGrammar)
 
 Converts a MatchVar into an expression by returning the variable directly.
 This is primarily useful for pretty-printing a pattern.
 """
-function matchnode2expr(pattern::MatchVar, ::Grammar)
+function matchnode2expr(pattern::MatchVar, ::AbstractGrammar)
 	return pattern.var_name
 end
 
 """
-    _matchnode2expr(expr::Expr, pattern::MatchNode, grammar::Grammar, j=0)
+    _matchnode2expr(expr::Expr, pattern::MatchNode, grammar::AbstractGrammar, j=0)
 
 Internal function for [`matchnode2expr`](@ref), recursively iterating over a matched pattern and converting it to an expression. This is primarily useful for pretty-printing a pattern. Returns the corresponding expression and the current child index.
 """
-function _matchnode2expr(expr::Expr, pattern::MatchNode, grammar::Grammar, j=0)
+function _matchnode2expr(expr::Expr, pattern::MatchNode, grammar::AbstractGrammar, j=0)
 	for (k,arg) ∈ enumerate(expr.args)
 		if isa(arg, Expr)
 			expr.args[k],j = _matchnode2expr(arg, pattern, grammar, j)
@@ -127,11 +127,11 @@ end
 
 
 """
-    _matchnode2expr(expr::Expr, pattern::MatchVar, grammar::Grammar, j=0)
+    _matchnode2expr(expr::Expr, pattern::MatchVar, grammar::AbstractGrammar, j=0)
 
 Internal function for [`matchnode2expr`](@ref), recursively iterating over a matched variable and converting it to an expression. This is primarily useful for pretty-printing a pattern. Returns the corresponding expression and the current child index.
 """
-function _matchnode2expr(expr::Expr, pattern::MatchVar, grammar::Grammar, j=0)
+function _matchnode2expr(expr::Expr, pattern::MatchVar, grammar::AbstractGrammar, j=0)
 	for (k,arg) ∈ enumerate(expr.args)
 		if isa(arg, Expr)
 			expr.args[k],j = _matchnode2expr(arg, pattern, grammar, j)
@@ -148,11 +148,11 @@ end
 
 
 """
-    _matchnode2expr(typ::Symbol, pattern::MatchNode, grammar::Grammar, j=0)
+    _matchnode2expr(typ::Symbol, pattern::MatchNode, grammar::AbstractGrammar, j=0)
 
 Internal function for [`matchnode2expr`](@ref), returning the matched translated symbol. This is primarily useful for pretty-printing a pattern. Returns the corresponding expression, i.e. the variable name and the current child index.
 """
-function _matchnode2expr(typ::Symbol, pattern::MatchNode, grammar::Grammar, j=0)
+function _matchnode2expr(typ::Symbol, pattern::MatchNode, grammar::AbstractGrammar, j=0)
 	retval = typ
     if haskey(grammar.bytype, typ)
         child = pattern.children[1]
@@ -170,11 +170,11 @@ end
 
 
 """
-    _matchnode2expr(typ::Symbol, pattern::MatchVar, grammar::Grammar, j=0)
+    _matchnode2expr(typ::Symbol, pattern::MatchVar, grammar::AbstractGrammar, j=0)
 
 Internal function for [`matchnode2expr`](@ref). This is primarily useful for pretty-printing a pattern. Returns the corresponding expression, i.e. the variable name and the current child index.
 """
-function _matchnode2expr(typ::Symbol, pattern::MatchVar, grammar::Grammar, j=0)
+function _matchnode2expr(typ::Symbol, pattern::MatchVar, grammar::AbstractGrammar, j=0)
 	return pattern.var_name, j
 end
 
diff --git a/src/propagatorconstraints/comesafter.jl b/src/propagatorconstraints/comesafter.jl
index 0908a16..7762169 100644
--- a/src/propagatorconstraints/comesafter.jl
+++ b/src/propagatorconstraints/comesafter.jl
@@ -34,7 +34,7 @@ Creates a [`ComesAfter`](@ref) constraint with only a single `predecessor`.
 ComesAfter(rule::Int, predecessor::Int) = ComesAfter(rule, [predecessor])
 
 """
-	propagate(c::ComesAfter, ::Grammar, context::GrammarContext, domain::Vector{Int})::Tuple{Vector{Int}, Vector{LocalConstraint}}
+	propagate(c::ComesAfter, ::AbstractGrammar, context::GrammarContext, domain::Vector{Int})::Tuple{Vector{Int}, Vector{LocalConstraint}}
 
 Propagates the [`ComesAfter`](@ref) [`PropagatorConstraint`](@ref).
 Rules in the domain that would violate the [`ComesAfter`](@ref) constraint are removed.
@@ -42,7 +42,7 @@ Rules in the domain that would violate the [`ComesAfter`](@ref) constraint are r
 
 function propagate(
     c::ComesAfter, 
-    ::Grammar, 
+    ::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
@@ -69,7 +69,7 @@ end
 """
 Checks if the given tree abides the constraint.
 """
-function check_tree(c::ComesAfter, g::Grammar, tree::AbstractRuleNode)::Bool
+function check_tree(c::ComesAfter, g::AbstractGrammar, tree::AbstractRuleNode)::Bool
 	@warn "ComesAfter.check_tree not implemented!"
 
 	return true
diff --git a/src/propagatorconstraints/condition.jl b/src/propagatorconstraints/condition.jl
index 0c314ed..d30cda2 100644
--- a/src/propagatorconstraints/condition.jl
+++ b/src/propagatorconstraints/condition.jl
@@ -1,12 +1,40 @@
+"""
+    Condition <: PropagatorConstraint
+
+This [`PropagatorConstraint`](@ref) forbids any subtree that matches the pattern defined by `tree` 
+and where the [`RuleNode`](@ref) that is matched to the variable in the pattern violates the predicate given by
+the `condition` function.
+
+The `condition` function takes a `RuleNode` tree and should return a `Bool`.
+
+!!! warning
+    The [`Condition`](@ref) constraint makes use of [`LocalConstraint`](@ref)s to make sure that constraints 
+    are also enforced in the future when the context of a [`Hole`](@ref) changes. 
+    Therefore, [`Condition`](@ref) can only be used in implementations that keep track of the 
+    [`LocalConstraint`](@ref)s and propagate them at the right moments.
+"""
 struct Condition <: PropagatorConstraint
     tree::AbstractMatchNode
     condition::Function
 end
     
 
+"""
+    propagate(c::Condition, g::AbstractGrammar, context::GrammarContext, domain::Vector{Int})::Tuple{Vector{Int}, Vector{LocalConstraint}}
+
+Propagates the [`Condition`](@ref) constraint.
+Rules that violate the [`Condition`](@ref) constraint are removed from the domain.
+
+!!! warning
+    The [`Condition`](@ref) constraint makes use of [`LocalConstraint`](@ref)s to make sure that constraints 
+    are also enforced in the future when the context of a [`Hole`](@ref) changes. 
+    Therefore, [`Condition`](@ref) can only be used in implementations that keep track of the 
+    [`LocalConstraint`](@ref)s and propagate them at the right moments.
+"""
+
 function propagate(
     c::Condition, 
-    g::Grammar, 
+    g::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
@@ -27,7 +55,7 @@ end
 """
 Checks if the given tree abides the constraint.
 """
-function check_tree(c::Condition, g::Grammar, tree::RuleNode)::Bool
+function check_tree(c::Condition, g::AbstractGrammar, tree::RuleNode)::Bool
     vars = Dict{Symbol, AbstractRuleNode}()
     
     # Return false if the node fits the pattern, but not the condition
@@ -38,6 +66,6 @@ function check_tree(c::Condition, g::Grammar, tree::RuleNode)::Bool
     return all(check_tree(c, g, child) for child ∈ tree.children)
 end
 
-function check_tree(::Condition, ::Grammar, ::Hole)::Bool
+function check_tree(::Condition, ::AbstractGrammar, ::Hole)::Bool
     return false
 end
diff --git a/src/propagatorconstraints/forbidden.jl b/src/propagatorconstraints/forbidden.jl
index d840126..aababcf 100644
--- a/src/propagatorconstraints/forbidden.jl
+++ b/src/propagatorconstraints/forbidden.jl
@@ -4,7 +4,7 @@
 This [`PropagatorConstraint`] forbids any subtree that matches the pattern given by `tree` to be generated.
 A pattern is a tree of [`AbstractMatchNode`](@ref)s. 
 Such a node can either be a [`MatchNode`](@ref), which contains a rule index corresponding to the 
-rule index in the [`Grammar`](@ref) and the appropriate number of children, similar to [`RuleNode`](@ref)s.
+rule index in the [`AbstractGrammar`](@ref) and the appropriate number of children, similar to [`RuleNode`](@ref)s.
 It can also contain a [`MatchVar`](@ref), which contains a single identifier symbol.
 A [`MatchVar`](@ref) can match any subtree, but if there are multiple instances of the same
 variable in the pattern, the matched subtrees must be identical.
@@ -31,7 +31,7 @@ end
 
 
 """
-    propagate(c::Forbidden, g::Grammar, context::GrammarContext, domain::Vector{Int})::Tuple{Vector{Int}, Vector{LocalConstraint}}
+    propagate(c::Forbidden, g::AbstractGrammar, context::GrammarContext, domain::Vector{Int})::Tuple{Vector{Int}, Vector{LocalConstraint}}
 
 Propagates the [`Forbidden`](@ref) constraint.
 It removes the rules from the `domain` that would complete the forbidden tree.
@@ -44,7 +44,7 @@ It removes the rules from the `domain` that would complete the forbidden tree.
 """
 function propagate(
     c::Forbidden, 
-    g::Grammar, 
+    g::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
@@ -62,11 +62,11 @@ function propagate(
 end
 
 """
-    check_tree(c::Forbidden, g::Grammar, tree::RuleNode)::Bool
+    check_tree(c::Forbidden, g::AbstractGrammar, tree::RuleNode)::Bool
 
 Checks if the given [`AbstractRuleNode`](@ref) tree abides the [`Forbidden`](@ref) constraint.
 """
-function check_tree(c::Forbidden, g::Grammar, tree::RuleNode)::Bool
+function check_tree(c::Forbidden, g::AbstractGrammar, tree::RuleNode)::Bool
     vars = Dict{Symbol, AbstractRuleNode}()
     if _pattern_match(tree, c.tree, vars) ≡ nothing
         return false
@@ -74,7 +74,7 @@ function check_tree(c::Forbidden, g::Grammar, tree::RuleNode)::Bool
     return all(check_tree(c, g, child) for child ∈ tree.children)
 end
 
-function check_tree(c::Forbidden, ::Grammar, tree::Hole)::Bool
+function check_tree(c::Forbidden, ::AbstractGrammar, tree::Hole)::Bool
     vars = Dict{Symbol, AbstractRuleNode}()
     return _pattern_match(tree, c.tree, vars) !== nothing
 end
diff --git a/src/propagatorconstraints/forbidden_path.jl b/src/propagatorconstraints/forbidden_path.jl
index b842c20..76e3f2d 100644
--- a/src/propagatorconstraints/forbidden_path.jl
+++ b/src/propagatorconstraints/forbidden_path.jl
@@ -24,7 +24,7 @@ It removes the elements from the domain that would complete the forbidden sequen
 """
 function propagate(
     c::ForbiddenPath, 
-    ::Grammar, 
+    ::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
@@ -48,7 +48,7 @@ end
 """
 Checks if the given tree abides the constraint.
 """
-function check_tree(c::ForbiddenPath, g::Grammar, tree::AbstractRuleNode)::Bool
+function check_tree(c::ForbiddenPath, g::AbstractGrammar, tree::AbstractRuleNode)::Bool
 	@warn "ForbiddenPath.check_tree not implemented!"
 
 	return true
diff --git a/src/propagatorconstraints/one_of.jl b/src/propagatorconstraints/one_of.jl
index 0fb6c5a..375b6e8 100644
--- a/src/propagatorconstraints/one_of.jl
+++ b/src/propagatorconstraints/one_of.jl
@@ -15,7 +15,7 @@ It enforces that at least one of its given constraints hold.
 """
 function propagate(
     c::OneOf, 
-    g::Grammar, 
+    g::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
@@ -32,6 +32,6 @@ end
 """
 Checks if the given tree abides the constraint.
 """
-function check_tree(c::OneOf, g::Grammar, tree::AbstractRuleNode)::Bool
+function check_tree(c::OneOf, g::AbstractGrammar, tree::AbstractRuleNode)::Bool
     return any(check_tree(cons, g, tree) for cons in c.constraints)
 end
diff --git a/src/propagatorconstraints/ordered.jl b/src/propagatorconstraints/ordered.jl
index f1e02bf..58fdf86 100644
--- a/src/propagatorconstraints/ordered.jl
+++ b/src/propagatorconstraints/ordered.jl
@@ -5,7 +5,7 @@ A [`PropagatorConstraint`](@ref) that enforces a specific order in [`MatchVar`](
 assignments in the pattern defined by `tree`.
 A pattern is a tree of [`AbstractMatchNode`](@ref)s. 
 Such a node can either be a [`MatchNode`](@ref), which contains a rule index corresponding to the 
-rule index in the [`Grammar`](@ref) and the appropriate number of children, similar to [`RuleNode`](@ref)s.
+rule index in the [`AbstractGrammar`](@ref) and the appropriate number of children, similar to [`RuleNode`](@ref)s.
 It can also contain a [`MatchVar`](@ref), which contains a single identifier symbol.
 A [`MatchVar`](@ref) can match any subtree, but if there are multiple instances of the same
 variable in the pattern, the matched subtrees must be identical.
@@ -38,7 +38,7 @@ end
 
 
 """
-    propagate(c::Ordered, g::Grammar, context::GrammarContext, domain::Vector{Int})::Tuple{Vector{Int}, Vector{LocalConstraint}}
+    propagate(c::Ordered, g::AbstractGrammar, context::GrammarContext, domain::Vector{Int})::Tuple{Vector{Int}, Vector{LocalConstraint}}
 
 Propagates the [`Ordered`](@ref) constraint.
 Any rule that violates the order as defined by the contraint is removed from the `domain`.
@@ -51,7 +51,7 @@ Any rule that violates the order as defined by the contraint is removed from the
 """
 function propagate(
     c::Ordered, 
-    g::Grammar, 
+    g::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
@@ -69,11 +69,11 @@ function propagate(
 end
 
 """
-    check_tree(c::Ordered, g::Grammar, tree::RuleNode)::Bool
+    check_tree(c::Ordered, g::AbstractGrammar, tree::RuleNode)::Bool
 
 Checks if the given [`AbstractRuleNode`](@ref) tree abides the [`Ordered`](@ref) constraint.
 """
-function check_tree(c::Ordered, g::Grammar, tree::RuleNode)::Bool
+function check_tree(c::Ordered, g::AbstractGrammar, tree::RuleNode)::Bool
     vars = Dict{Symbol, AbstractRuleNode}()
     if _pattern_match(tree, c.tree, vars) ≡ nothing
         # Check variable ordering
@@ -84,4 +84,4 @@ function check_tree(c::Ordered, g::Grammar, tree::RuleNode)::Bool
     return all(check_tree(c, g, child) for child ∈ tree.children)
 end
 
-check_tree(c::Ordered, g::Grammar, tree::Hole)::Bool = true
+check_tree(c::Ordered, g::AbstractGrammar, tree::Hole)::Bool = true
diff --git a/src/propagatorconstraints/require_on_left.jl b/src/propagatorconstraints/require_on_left.jl
index 8875d3a..cec70c6 100644
--- a/src/propagatorconstraints/require_on_left.jl
+++ b/src/propagatorconstraints/require_on_left.jl
@@ -14,7 +14,7 @@ predecessor in the left subtree.
 """
 function propagate(
     c::RequireOnLeft, 
-    ::Grammar, 
+    ::AbstractGrammar, 
     context::GrammarContext, 
     domain::Vector{Int}, 
     filled_hole::Union{HoleReference, Nothing}
@@ -43,7 +43,7 @@ end
 """
 Checks if the given tree abides the constraint.
 """
-function check_tree(c::RequireOnLeft, g::Grammar, tree::AbstractRuleNode)::Bool
+function check_tree(c::RequireOnLeft, g::AbstractGrammar, tree::AbstractRuleNode)::Bool
 	@warn "RequireOnLeft.check_tree not implemented!"
 
 	return true