diff --git a/src/main/java/com/clevercloud/biscuit/datalog/AuthorizedWorld.java b/src/main/java/com/clevercloud/biscuit/datalog/AuthorizedWorld.java
deleted file mode 100644
index 0058fb0a..00000000
--- a/src/main/java/com/clevercloud/biscuit/datalog/AuthorizedWorld.java
+++ /dev/null
@@ -1,14 +0,0 @@
-package com.clevercloud.biscuit.datalog;
-
-import java.util.Set;
-
-public class AuthorizedWorld extends World {
-
-    public AuthorizedWorld(FactSet facts) {
-        super(facts);
-    }
-
-    /*public final Set<Fact> queryAll(final Rule rule, SymbolTable symbols) {
-        return this.query_rule(rule, symbols);
-    }*/
-}
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java b/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java
index 3f11261a..309d6241 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/Combinator.java
@@ -22,7 +22,7 @@ public final class Combinator implements Serializable, Iterator<Tuple2<Origin, M
 
    @Override
    public boolean hasNext() {
-      if(this.nextElement != null && this.nextElement.isDefined()) {
+      if (this.nextElement != null && this.nextElement.isDefined()) {
          return true;
       }
       this.nextElement = getNext();
@@ -31,10 +31,10 @@ public boolean hasNext() {
 
    @Override
    public Tuple2<Origin, Map<Long, Term>> next() {
-      if(this.nextElement == null || !this.nextElement.isDefined()) {
+      if (this.nextElement == null || !this.nextElement.isDefined()) {
          this.nextElement = getNext();
       }
-      if(this.nextElement == null || !this.nextElement.isDefined()) {
+      if (this.nextElement == null || !this.nextElement.isDefined()) {
          throw new NoSuchElementException();
       } else {
          Tuple2<Origin, Map<Long, Term>> t = this.nextElement.get();
@@ -46,7 +46,7 @@ public Tuple2<Origin, Map<Long, Term>> next() {
    public Option<Tuple2<Origin, Map<Long, Term>>> getNext() {
       if (this.predicates.isEmpty()) {
          final Option<Map<Long, Term>> v_opt = this.variables.complete();
-         if(v_opt.isEmpty()) {
+         if (v_opt.isEmpty()) {
             return Option.none();
          } else {
             Map<Long, Term> variables = v_opt.get();
@@ -55,14 +55,14 @@ public Option<Tuple2<Origin, Map<Long, Term>>> getNext() {
             // successful calls, we create a set of variables that cannot
             // possibly be completed, so the next call will fail
             Set<Long> set = new HashSet();
-            set.add((long)0);
+            set.add((long) 0);
 
             this.variables = new MatchedVariables(set);
             return Option.some(new Tuple2(new Origin(), variables));
          }
       }
 
-      while(true) {
+      while (true) {
          if (this.currentIt == null) {
             Predicate predicate = this.predicates.get(0);
 
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/FactSet.java b/src/main/java/com/clevercloud/biscuit/datalog/FactSet.java
index 07e41e40..730bf828 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/FactSet.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/FactSet.java
@@ -3,7 +3,6 @@
 import io.vavr.Tuple2;
 
 import java.util.*;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 public class FactSet {
@@ -55,7 +54,7 @@ public void merge(FactSet other) {
             }
         }
     }
-    public Stream iterator(TrustedOrigins blockIds) {
+    public Stream stream(TrustedOrigins blockIds) {
         return facts.entrySet()
                 .stream()
                 .filter(entry -> {
@@ -67,7 +66,7 @@ public Stream iterator(TrustedOrigins blockIds) {
                         .map(fact -> new Tuple2(entry.getKey(), fact)));
     }
 
-    public Stream<Fact> iterator() {
+    public Stream<Fact> stream() {
         return facts.entrySet()
                 .stream()
                 .flatMap(entry -> entry.getValue()
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/Rule.java b/src/main/java/com/clevercloud/biscuit/datalog/Rule.java
index ba367c66..8c4834be 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/Rule.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/Rule.java
@@ -50,56 +50,50 @@ public Stream<Either<Error, Tuple2<Origin, Fact>>> apply(
               .spliteratorUnknownSize(combinator, Spliterator.ORDERED);
       Stream<Tuple2<Origin, Map<Long, Term>>> stream = StreamSupport.stream(splitItr, false);
 
-       //somehow we have inference errors when writing this as a lambda
-       return stream.map(t -> {
-         Origin origin = t._1;
-         Map<Long, Term> generatedVariables = t._2;
-         TemporarySymbolTable temporarySymbols = new TemporarySymbolTable(symbols);
-         for (Expression e : this.expressions) {
-            Option<Term> res = e.evaluate(generatedVariables, temporarySymbols);
-            if (res.isDefined()) {
-               Term term = res.get();
-               if (term instanceof Term.Bool) {
-                  Term.Bool b = (Term.Bool) term;
-                  if (!b.value()) {
-                     return Either.right(new Tuple3(origin, generatedVariables, false));
-                  }
-                  // continue evaluating if true
-               } else {
-                  return Either.left(new InvalidType());
-               }
-            }
-         }
-         return Either.right(new Tuple3(origin, generatedVariables, true));
-         /*
-      .filter((java.util.function.Predicate<? super Either<? extends Object, ? extends Object>>) new java.util.function.Predicate<Either<Error, Tuple3<Origin, Map<Long, Term>, Boolean>>>() {
-         //somehow we have inference errors when writing this as a lambda
-         @Override
-         public boolean test(Either<Error, Tuple3<Origin, Map<Long, Term>, Boolean>> res) {
-            return res.isRight() & res.get()._3.booleanValue();
-         }
-      })*/
-      }).filter((java.util.function.Predicate<? super Either<? extends Object, ? extends Object>>)
-               res -> res.isRight() & ((Tuple3<Origin, Map<Long, Term>, Boolean>)res.get())._3.booleanValue()).map(res -> {
-         Tuple3<Origin, Map<Long, Term>, Boolean> t = (Tuple3<Origin, Map<Long, Term>, Boolean>) res.get();
-         Origin origin = t._1;
-         Map<Long, Term> generatedVariables = t._2;
-
-         Predicate p = this.head.clone();
-         for (int index = 0; index < p.terms().size(); index++) {
-            if (p.terms().get(index) instanceof Term.Variable) {
-               Term.Variable var = (Term.Variable) p.terms().get(index);
-               if(!generatedVariables.containsKey(var.value())) {
-                  //throw new Error("variables that appear in the head should appear in the body as well");
-                  return Either.left(new Error.InternalError());
-               }
-               p.terms().set(index, generatedVariables.get(var.value()));
-            }
-         }
+      //somehow we have inference errors when writing this as a lambda
+      return stream.map(t -> {
+                 Origin origin = t._1;
+                 Map<Long, Term> generatedVariables = t._2;
+                 TemporarySymbolTable temporarySymbols = new TemporarySymbolTable(symbols);
+                 for (Expression e : this.expressions) {
+                    Option<Term> res = e.evaluate(generatedVariables, temporarySymbols);
+                    if (res.isDefined()) {
+                       Term term = res.get();
+                       if (term instanceof Term.Bool) {
+                          Term.Bool b = (Term.Bool) term;
+                          if (!b.value()) {
+                             return Either.right(new Tuple3(origin, generatedVariables, false));
+                          }
+                          // continue evaluating if true
+                       } else {
+                          return Either.left(new InvalidType());
+                       }
+                    }
+                 }
+                 return Either.right(new Tuple3(origin, generatedVariables, true));
+              })
+              // sometimes we need to make the compiler happy
+              .filter((java.util.function.Predicate<? super Either<? extends Object, ? extends Object>>)
+                      res -> res.isRight() & ((Tuple3<Origin, Map<Long, Term>, Boolean>) res.get())._3.booleanValue()).map(res -> {
+                 Tuple3<Origin, Map<Long, Term>, Boolean> t = (Tuple3<Origin, Map<Long, Term>, Boolean>) res.get();
+                 Origin origin = t._1;
+                 Map<Long, Term> generatedVariables = t._2;
+
+                 Predicate p = this.head.clone();
+                 for (int index = 0; index < p.terms().size(); index++) {
+                    if (p.terms().get(index) instanceof Term.Variable) {
+                       Term.Variable var = (Term.Variable) p.terms().get(index);
+                       if (!generatedVariables.containsKey(var.value())) {
+                          //throw new Error("variables that appear in the head should appear in the body as well");
+                          return Either.left(new Error.InternalError());
+                       }
+                       p.terms().set(index, generatedVariables.get(var.value()));
+                    }
+                 }
 
-         origin.add(ruleOrigin);
-         return Either.right(new Tuple2<Origin, Fact>(origin, new Fact(p)));
-      });
+                 origin.add(ruleOrigin);
+                 return Either.right(new Tuple2<Origin, Fact>(origin, new Fact(p)));
+              });
    }
 
    private MatchedVariables variablesSet() {
@@ -119,7 +113,7 @@ public boolean find_match(final FactSet facts, Long origin, TrustedOrigins scope
          return variables.check_expressions(this.expressions, symbols).isDefined();
       }
 
-      Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> facts.iterator(scope);
+      Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> facts.stream(scope);
       Stream<Either<Error, Tuple2<Origin, Fact>>> stream = this.apply(factsSupplier, origin, symbols);
 
       Iterator<Either<Error, Tuple2<Origin, Fact>>> it = stream.iterator();
@@ -144,7 +138,7 @@ public boolean check_match_all(final FactSet facts, TrustedOrigins scope, Symbol
          return variables.check_expressions(this.expressions, symbols).isDefined();
       }
 
-      Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> facts.iterator(scope);
+      Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> facts.stream(scope);
       Combinator combinator = new Combinator(variables, this.body, factsSupplier, symbols);
       boolean found = false;
 
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/RuleSet.java b/src/main/java/com/clevercloud/biscuit/datalog/RuleSet.java
index e4bd56f1..5c850bee 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/RuleSet.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/RuleSet.java
@@ -13,7 +13,7 @@ public RuleSet() {
     }
 
     public void add(Long origin, TrustedOrigins scope, Rule rule) {
-        if(!rules.containsKey(scope)) {
+        if (!rules.containsKey(scope)) {
             rules.put(scope, Arrays.asList(new Tuple2(origin, rule)));
         } else {
             rules.get(scope).add(new Tuple2(origin, rule));
@@ -23,7 +23,7 @@ public void add(Long origin, TrustedOrigins scope, Rule rule) {
     public RuleSet clone() {
         RuleSet newRules = new RuleSet();
 
-        for(Map.Entry<TrustedOrigins, List<Tuple2<Long, Rule>>> entry: this.rules.entrySet()) {
+        for (Map.Entry<TrustedOrigins, List<Tuple2<Long, Rule>>> entry : this.rules.entrySet()) {
             List<Tuple2<Long, Rule>> l = new ArrayList<>();
             l.addAll(entry.getValue());
             newRules.rules.put(entry.getKey(), l);
@@ -32,13 +32,14 @@ public RuleSet clone() {
         return newRules;
     }
 
-    public Stream<Rule> iterator() {
+    public Stream<Rule> stream() {
         return rules.entrySet()
                 .stream()
                 .flatMap(entry -> entry.getValue()
                         .stream()
                         .map(t -> t._2));
     }
+
     public void clear() {
         rules.clear();
     }
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/SchemaVersion.java b/src/main/java/com/clevercloud/biscuit/datalog/SchemaVersion.java
index 6c185231..ed7fed73 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/SchemaVersion.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/SchemaVersion.java
@@ -18,21 +18,20 @@ public class SchemaVersion {
     private boolean containsV4;
 
     public SchemaVersion(List<Fact> facts, List<Rule> rules, List<Check> checks, List<Scope> scopes) {
-        // TODO
         containsScopes = !scopes.isEmpty();
 
-        if(!containsScopes) {
-            for(Rule r: rules) {
+        if (!containsScopes) {
+            for (Rule r : rules) {
                 if (!r.scopes().isEmpty()) {
                     containsScopes = true;
                     break;
                 }
             }
         }
-        if(!containsScopes) {
-            for(Check check: checks) {
-                for(Rule query: check.queries()) {
-                    if(!query.scopes().isEmpty()) {
+        if (!containsScopes) {
+            for (Check check : checks) {
+                for (Rule query : check.queries()) {
+                    if (!query.scopes().isEmpty()) {
                         containsScopes = true;
                         break;
                     }
@@ -41,7 +40,7 @@ public SchemaVersion(List<Fact> facts, List<Rule> rules, List<Check> checks, Lis
         }
 
         containsCheckAll = false;
-        for(Check check: checks) {
+        for (Check check : checks) {
             if (check.kind() == All) {
                 containsCheckAll = true;
                 break;
@@ -49,8 +48,8 @@ public SchemaVersion(List<Fact> facts, List<Rule> rules, List<Check> checks, Lis
         }
 
         containsV4 = false;
-        for(Check check: checks) {
-            for(Rule query: check.queries()) {
+        for (Check check : checks) {
+            for (Rule query : check.queries()) {
                 if (containsV4Ops(query.expressions())) {
                     containsV4 = true;
                     break;
@@ -61,7 +60,7 @@ public SchemaVersion(List<Fact> facts, List<Rule> rules, List<Check> checks, Lis
 
     public int version() {
         if (containsScopes || containsV4 || containsCheckAll) {
-          return  4;
+            return 4;
         } else {
             return MIN_SCHEMA_VERSION;
         }
@@ -72,10 +71,10 @@ public Either<Error.FormatError, Void> checkCompatibility(int version) {
             if (containsScopes) {
                 return Left(new Error.FormatError.DeserializationError("v3 blocks must not have scopes"));
             }
-            if(containsV4) {
+            if (containsV4) {
                 return Left(new Error.FormatError.DeserializationError("v3 blocks must not have v4 operators (bitwise operators or !="));
             }
-            if(containsCheckAll) {
+            if (containsCheckAll) {
                 return Left(new Error.FormatError.DeserializationError("v3 blocks must not use check all"));
             }
         }
@@ -84,8 +83,8 @@ public Either<Error.FormatError, Void> checkCompatibility(int version) {
     }
 
     public static boolean containsV4Ops(List<Expression> expressions) {
-        for(Expression e: expressions) {
-            for (Op op: e.getOps()) {
+        for (Expression e : expressions) {
+            for (Op op : e.getOps()) {
                 if (op instanceof Op.Binary) {
                     Op.Binary b = (Op.Binary) op;
                     switch (b.getOp()) {
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/Scope.java b/src/main/java/com/clevercloud/biscuit/datalog/Scope.java
index 9ca131cc..6a9e045c 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/Scope.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/Scope.java
@@ -1,11 +1,9 @@
 package com.clevercloud.biscuit.datalog;
 
 import biscuit.format.schema.Schema;
-import com.clevercloud.biscuit.datalog.expressions.Expression;
 import com.clevercloud.biscuit.error.Error;
 import io.vavr.control.Either;
 
-import java.util.ArrayList;
 
 import static io.vavr.API.Left;
 import static io.vavr.API.Right;
@@ -24,6 +22,7 @@ private Scope(Kind kind, long publicKey) {
         this.kind = kind;
         this.publicKey = publicKey;
     }
+
     public static Scope authority() {
         return new Scope(Kind.Authority, 0);
     }
@@ -47,7 +46,7 @@ public long publicKey() {
     public Schema.Scope serialize() {
         Schema.Scope.Builder b = Schema.Scope.newBuilder();
 
-        switch(this.kind) {
+        switch (this.kind) {
             case Authority:
                 b.setScopeType(Schema.Scope.ScopeType.Authority);
                 break;
@@ -66,8 +65,8 @@ static public Either<Error.FormatError, Scope> deserialize(Schema.Scope scope) {
             long publicKey = scope.getPublicKey();
             return Right(Scope.publicKey(publicKey));
         }
-        if(scope.hasScopeType()) {
-            switch(scope.getScopeType()) {
+        if (scope.hasScopeType()) {
+            switch (scope.getScopeType()) {
                 case Authority:
                     return Right(Scope.authority());
                 case Previous:
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/SymbolTable.java b/src/main/java/com/clevercloud/biscuit/datalog/SymbolTable.java
index 480c8d5d..69b38976 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/SymbolTable.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/SymbolTable.java
@@ -229,8 +229,8 @@ public String print_check(final Check c) {
     }
 
     public String print_world(final World w) {
-        final List<String> facts = w.facts().iterator().map((f) -> this.print_fact(f)).collect(Collectors.toList());
-        final List<String> rules = w.rules().iterator().map((r) -> this.print_rule(r)).collect(Collectors.toList());
+        final List<String> facts = w.facts().stream().map((f) -> this.print_fact(f)).collect(Collectors.toList());
+        final List<String> rules = w.rules().stream().map((r) -> this.print_rule(r)).collect(Collectors.toList());
 
         StringBuilder b = new StringBuilder();
         b.append("World {\n\tfacts: [\n\t\t");
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/TemporarySymbolTable.java b/src/main/java/com/clevercloud/biscuit/datalog/TemporarySymbolTable.java
index d9055085..deaff85c 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/TemporarySymbolTable.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/TemporarySymbolTable.java
@@ -19,8 +19,8 @@ public TemporarySymbolTable(SymbolTable base) {
     }
 
     public Option<String> get_s(int i) {
-        if(i >= this.offset) {
-            if(i - this.offset < this.symbols.size()) {
+        if (i >= this.offset) {
+            if (i - this.offset < this.symbols.size()) {
                 return Option.some(this.symbols.get(i - this.offset));
             } else {
                 return Option.none();
@@ -32,12 +32,12 @@ public Option<String> get_s(int i) {
 
     public long insert(final String symbol) {
         Option<Long> opt = this.base.get(symbol);
-        if(opt.isDefined()) {
+        if (opt.isDefined()) {
             return opt.get().longValue();
         }
 
         int index = this.symbols.indexOf(symbol);
-        if(index != -1) {
+        if (index != -1) {
             return (long) (this.offset + index);
         }
         this.symbols.add(symbol);
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/TrustedOrigins.java b/src/main/java/com/clevercloud/biscuit/datalog/TrustedOrigins.java
index 6597a24e..2af85f58 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/TrustedOrigins.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/TrustedOrigins.java
@@ -7,9 +7,9 @@
 public class TrustedOrigins {
     private Origin inner;
 
-    public TrustedOrigins(int ... origins) {
+    public TrustedOrigins(int... origins) {
         Origin origin = new Origin();
-        for(int i: origins) {
+        for (int i : origins) {
             origin.add(i);
         }
         inner = origin;
@@ -20,7 +20,7 @@ private TrustedOrigins() {
     }
 
     private TrustedOrigins(Origin inner) {
-        if(inner == null) {
+        if (inner == null) {
             throw new RuntimeException();
         }
         this.inner = inner;
@@ -29,6 +29,7 @@ private TrustedOrigins(Origin inner) {
     public TrustedOrigins clone() {
         return new TrustedOrigins(this.inner.clone());
     }
+
     public static TrustedOrigins defaultOrigins() {
         TrustedOrigins origins = new TrustedOrigins();
         origins.inner.add(0);
@@ -51,21 +52,21 @@ public static TrustedOrigins fromScopes(List<Scope> ruleScopes,
         origins.inner.add(currentBlock);
         origins.inner.add(Long.MAX_VALUE);
 
-        for(Scope scope: ruleScopes) {
+        for (Scope scope : ruleScopes) {
             switch (scope.kind()) {
                 case Authority:
                     origins.inner.add(0);
                     break;
                 case Previous:
-                    if(currentBlock != Long.MAX_VALUE) {
-                        for(long i = 0; i < currentBlock+1; i++) {
+                    if (currentBlock != Long.MAX_VALUE) {
+                        for (long i = 0; i < currentBlock + 1; i++) {
                             origins.inner.add(i);
                         }
                     }
                     break;
                 case PublicKey:
                     List<Long> blockIds = publicKeyToBlockId.get(scope.publicKey());
-                    if(blockIds != null) {
+                    if (blockIds != null) {
                         origins.inner.inner.addAll(blockIds);
                     }
             }
diff --git a/src/main/java/com/clevercloud/biscuit/datalog/World.java b/src/main/java/com/clevercloud/biscuit/datalog/World.java
index 357b6d85..a8be5a80 100644
--- a/src/main/java/com/clevercloud/biscuit/datalog/World.java
+++ b/src/main/java/com/clevercloud/biscuit/datalog/World.java
@@ -1,6 +1,5 @@
 package com.clevercloud.biscuit.datalog;
 
-import com.clevercloud.biscuit.datalog.expressions.Expression;
 import com.clevercloud.biscuit.error.Error;
 import io.vavr.Tuple2;
 import io.vavr.control.Either;
@@ -9,7 +8,6 @@
 import java.time.Instant;
 import java.util.*;
 import java.util.function.Supplier;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 public class World implements Serializable {
@@ -45,7 +43,7 @@ public void run(RunLimits limits, final SymbolTable symbols) throws Error {
 
          for(Map.Entry<TrustedOrigins, List<Tuple2<Long, Rule>>> entry: this.rules.rules.entrySet()) {
             for(Tuple2<Long, Rule> t: entry.getValue()) {
-               Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> this.facts.iterator(entry.getKey());
+               Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> this.facts.stream(entry.getKey());
 
                Stream<Either<Error, Tuple2<Origin, Fact>>> stream =  t._2.apply(factsSupplier, t._1, symbols);
                 for (Iterator<Either<Error, Tuple2<Origin, Fact>>> it = stream.iterator(); it.hasNext(); ) {
@@ -89,33 +87,10 @@ public final FactSet facts() {
 
    public RuleSet rules() { return this.rules; }
 
-   /*public final Set<Fact> query(final Predicate pred) {
-      return this.facts.stream().filter((f) -> {
-         if (f.predicate().name() != pred.name()) {
-            return false;
-         }
-         final int min_size = Math.min(f.predicate().terms().size(), pred.terms().size());
-         for (int i = 0; i < min_size; ++i) {
-            final Term fid = f.predicate().terms().get(i);
-            final Term pid = pred.terms().get(i);
-            if ((fid instanceof Term.Integer || fid instanceof Term.Str || fid instanceof Term.Date)
-                    && fid.getClass() == pid.getClass()) {
-               if (!fid.equals(pid)) {
-                  return false;
-               }
-            // FIXME: is it still necessary?
-            //} else if (!(fid instanceof Term.Symbol && pid instanceof Term.Variable)) {
-            //   return false;
-            }
-         }
-         return true;
-      }).collect(Collectors.toSet());
-   }*/
-
    public final FactSet query_rule(final Rule rule, Long origin, TrustedOrigins scope, SymbolTable symbols) throws Error {
       final FactSet newFacts = new FactSet();
 
-      Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> this.facts.iterator(scope);
+      Supplier<Stream<Tuple2<Origin, Fact>>> factsSupplier = () -> this.facts.stream(scope);
 
       Stream<Either<Error, Tuple2<Origin, Fact>>> stream = rule.apply(factsSupplier, origin, symbols);
       for (Iterator<Either<Error, Tuple2<Origin, Fact>>> it = stream.iterator(); it.hasNext(); ) {
@@ -171,14 +146,14 @@ public String print(SymbolTable symbol_table) {
       StringBuilder s = new StringBuilder();
 
       s.append("World {\n\t\tfacts: [");
-       for (Iterator<Fact> it = this.facts.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = this.facts.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            s.append("\n\t\t\t");
            s.append(symbol_table.print_fact(f));
        }
 
       s.append("\n\t\t]\n\t\trules: [");
-       for (Iterator<Rule> it = this.rules.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Rule> it = this.rules.stream().iterator(); it.hasNext(); ) {
            Rule r = it.next();
            s.append("\n\t\t\t");
            s.append(symbol_table.print_rule(r));
diff --git a/src/main/java/com/clevercloud/biscuit/token/Authorizer.java b/src/main/java/com/clevercloud/biscuit/token/Authorizer.java
index 8f0744fb..5c79d1ab 100644
--- a/src/main/java/com/clevercloud/biscuit/token/Authorizer.java
+++ b/src/main/java/com/clevercloud/biscuit/token/Authorizer.java
@@ -305,7 +305,7 @@ public Set<Fact> query(Rule query, RunLimits limits) throws Error {
                 ruleTrustedorigins, symbols);
         Set<Fact> s = new HashSet<>();
 
-        for (Iterator it = facts.iterator().iterator(); it.hasNext(); ) {
+        for (Iterator it = facts.stream().iterator(); it.hasNext(); ) {
             com.clevercloud.biscuit.datalog.Fact f = (com.clevercloud.biscuit.datalog.Fact) it.next();
             s.add(Fact.convert_from(f, symbols));
         }
@@ -565,8 +565,8 @@ public Long authorize(RunLimits limits) throws Error {
 
     public String print_world() {
         //FIXME
-        final List<String> facts = this.world.facts().iterator().map((f) -> this.symbols.print_fact(f)).collect(Collectors.toList());
-        final List<String> rules = this.world.rules().iterator().map((r) -> this.symbols.print_rule(r)).collect(Collectors.toList());
+        final List<String> facts = this.world.facts().stream().map((f) -> this.symbols.print_fact(f)).collect(Collectors.toList());
+        final List<String> rules = this.world.rules().stream().map((r) -> this.symbols.print_rule(r)).collect(Collectors.toList());
 
         List<String> checks = new ArrayList<>();
 
diff --git a/src/main/java/com/clevercloud/biscuit/token/builder/Scope.java b/src/main/java/com/clevercloud/biscuit/token/builder/Scope.java
index bec24afc..d8167eae 100644
--- a/src/main/java/com/clevercloud/biscuit/token/builder/Scope.java
+++ b/src/main/java/com/clevercloud/biscuit/token/builder/Scope.java
@@ -36,11 +36,13 @@ private Scope(Kind kind, PublicKey publicKey) {
         this.publicKey = publicKey;
         this.parameter = new String();
     }
+
     private Scope(Kind kind, String parameter) {
         this.kind = kind;
         this.publicKey = null;
         this.parameter = parameter;
     }
+
     public static Scope authority() {
         return new Scope(Kind.Authority);
     }
@@ -66,7 +68,7 @@ public com.clevercloud.biscuit.datalog.Scope convert(SymbolTable symbols) {
             case Parameter:
                 //FIXME
                 return null;
-                //throw new Exception("Remaining parameter: "+this.parameter);
+            //throw new Exception("Remaining parameter: "+this.parameter);
             case PublicKey:
                 return com.clevercloud.biscuit.datalog.Scope.publicKey(symbols.insert(this.publicKey));
         }
@@ -75,7 +77,7 @@ public com.clevercloud.biscuit.datalog.Scope convert(SymbolTable symbols) {
     }
 
     public static Scope convert_from(com.clevercloud.biscuit.datalog.Scope scope, SymbolTable symbols) {
-        switch(scope.kind()) {
+        switch (scope.kind()) {
             case Authority:
                 return new Scope(Kind.Authority);
             case Previous:
@@ -119,7 +121,7 @@ public String toString() {
             case Previous:
                 return "previous";
             case Parameter:
-                return "{"+this.parameter+"}";
+                return "{" + this.parameter + "}";
             case PublicKey:
                 return this.publicKey.toString();
         }
diff --git a/src/test/java/com/clevercloud/biscuit/datalog/WorldTest.java b/src/test/java/com/clevercloud/biscuit/datalog/WorldTest.java
index ce566b2d..6c25f4a7 100644
--- a/src/test/java/com/clevercloud/biscuit/datalog/WorldTest.java
+++ b/src/test/java/com/clevercloud/biscuit/datalog/WorldTest.java
@@ -38,8 +38,8 @@ public void testFamily() throws Error {
 
       System.out.println("testing r1: " + syms.print_rule(r1));
       FactSet query_rule_result = w.query_rule(r1, (long)0, new TrustedOrigins(0), syms);
-      System.out.println("grandparents query_rules: [" + String.join(", ", query_rule_result.iterator().map((f) -> syms.print_fact(f)).collect(Collectors.toList())) + "]");
-      System.out.println("current facts: [" + String.join(", ", w.facts().iterator().map((f) -> syms.print_fact(f)).collect(Collectors.toList())) + "]");
+      System.out.println("grandparents query_rules: [" + String.join(", ", query_rule_result.stream().map((f) -> syms.print_fact(f)).collect(Collectors.toList())) + "]");
+      System.out.println("current facts: [" + String.join(", ", w.facts().stream().map((f) -> syms.print_fact(f)).collect(Collectors.toList())) + "]");
 
       final Rule r2 = new Rule(new Predicate(grandparent,
               Arrays.asList(new Term.Variable(syms.insert("grandparent")), new Term.Variable(syms.insert("grandchild")))), Arrays.asList(
@@ -58,7 +58,7 @@ public void testFamily() throws Error {
                       Arrays.asList(new Term.Variable(syms.insert("parent")), new Term.Variable(syms.insert("child"))))),
               new ArrayList<>());
 
-      for (Iterator<Fact> it = w.query_rule(query1, (long) 0, new TrustedOrigins(0), syms).iterator().iterator(); it.hasNext(); ) {
+      for (Iterator<Fact> it = w.query_rule(query1, (long) 0, new TrustedOrigins(0), syms).stream().iterator(); it.hasNext(); ) {
          Fact fact = it.next();
          System.out.println("\t" + syms.print_fact(fact));
       }
@@ -67,7 +67,7 @@ public void testFamily() throws Error {
               new ArrayList<>());
       System.out.println("parents of B: [" + String.join(", ",
               w.query_rule(query2, (long) 0, new TrustedOrigins(0), syms)
-                      .iterator().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
+                      .stream().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
       final Rule query3 = new Rule(new Predicate(grandparent, Arrays.asList(new Term.Variable(syms.insert("grandparent")),
               new Term.Variable(syms.insert("grandchild")))),
               Arrays.asList(new Predicate(grandparent, Arrays.asList(new Term.Variable(syms.insert("grandparent")),
@@ -75,7 +75,7 @@ public void testFamily() throws Error {
               new ArrayList<>());
       System.out.println("grandparents: [" + String.join(", ",
               w.query_rule(query3, (long) 0, new TrustedOrigins(0), syms)
-                      .iterator().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
+                      .stream().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
 
       w.add_fact(new Origin(0), new Fact(new Predicate(parent, Arrays.asList(c, e))));
       w.run(syms);
@@ -87,7 +87,7 @@ public void testFamily() throws Error {
               new ArrayList<>());
       final FactSet res = w.query_rule(query4, (long) 0, new TrustedOrigins(0), syms);
       System.out.println("grandparents after inserting parent(C, E): [" + String.join(", ",
-              res.iterator().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
+              res.stream().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
 
       final FactSet expected = new FactSet(new Origin(0), new HashSet<>(Arrays.asList(
               new Fact(new Predicate(grandparent, Arrays.asList(a, c))),
@@ -111,7 +111,7 @@ public void testFamily() throws Error {
               new ArrayList<>());
       System.out.println("siblings: [" + String.join(", ",
               w.query_rule(query5, (long) 0, new TrustedOrigins(0), syms)
-                      .iterator().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
+                      .stream().map((f) -> syms.print_fact(f)).collect(Collectors.toSet())) + "]");
    }
 
    @Test
@@ -151,7 +151,7 @@ public void testNumbers() throws Error {
                                     new Term.Variable(syms.insert("right")),
                                     new Term.Variable(syms.insert("id"))))), new ArrayList<>()),
               (long) 0, new TrustedOrigins(0), syms);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -174,7 +174,7 @@ public void testNumbers() throws Error {
                       new Op.Binary(Op.BinaryOp.LessThan)
                       ))))
       ), (long) 0, new TrustedOrigins(0), syms);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -218,7 +218,7 @@ public void testStr() throws Error {
       w.add_fact(new Origin(0), new Fact(new Predicate(route, Arrays.asList(new Term.Integer(4), app_1, syms.add("mx.example.com")))));
 
       FactSet res = testSuffix(w, syms, suff, route, ".fr");
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -227,7 +227,7 @@ public void testStr() throws Error {
       assertEquals(expected, res);
 
       res = testSuffix(w, syms, suff, route, "example.com");
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -286,7 +286,7 @@ public void testDate() throws Error {
 
       System.out.println("testing r1: " + syms.print_rule(r1));
       FactSet res = w.query_rule(r1, (long) 0, new TrustedOrigins(0), syms);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -315,7 +315,7 @@ public void testDate() throws Error {
 
       System.out.println("testing r2: " + syms.print_rule(r2));
       res = w.query_rule(r2, (long) 0, new TrustedOrigins(0), syms);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -355,7 +355,7 @@ public void testSet() throws Error {
       );
       System.out.println("testing r1: " + syms.print_rule(r1));
       FactSet res = w.query_rule(r1, (long) 0, new TrustedOrigins(0), syms);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -381,7 +381,7 @@ public void testSet() throws Error {
 
       System.out.println("testing r2: " + syms.print_rule(r2));
       res = w.query_rule(r2, (long) 0, new TrustedOrigins(0), syms);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -401,7 +401,7 @@ public void testSet() throws Error {
       );
       System.out.println("testing r3: " + syms.print_rule(r3));
       res = w.query_rule(r3, (long) 0, new TrustedOrigins(0), syms);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -439,7 +439,7 @@ public void testResource() throws Error {
       System.out.println("testing caveat 1(should return nothing): " + syms.print_rule(r1));
       FactSet res = w.query_rule(r1, (long) 0, new TrustedOrigins(0), syms);
       System.out.println(res);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
@@ -460,7 +460,7 @@ public void testResource() throws Error {
       System.out.println("testing caveat 2: " + syms.print_rule(r2));
       res = w.query_rule(r2, (long) 0, new TrustedOrigins(0), syms);
       System.out.println(res);
-       for (Iterator<Fact> it = res.iterator().iterator(); it.hasNext(); ) {
+       for (Iterator<Fact> it = res.stream().iterator(); it.hasNext(); ) {
            Fact f = it.next();
            System.out.println("\t" + syms.print_fact(f));
        }
diff --git a/src/test/java/com/clevercloud/biscuit/token/BiscuitTest.java b/src/test/java/com/clevercloud/biscuit/token/BiscuitTest.java
index 6848428f..fca634b5 100644
--- a/src/test/java/com/clevercloud/biscuit/token/BiscuitTest.java
+++ b/src/test/java/com/clevercloud/biscuit/token/BiscuitTest.java
@@ -3,8 +3,6 @@
 import com.clevercloud.biscuit.crypto.KeyDelegate;
 import com.clevercloud.biscuit.crypto.KeyPair;
 import com.clevercloud.biscuit.crypto.PublicKey;
-import com.clevercloud.biscuit.datalog.AuthorizedWorld;
-import com.clevercloud.biscuit.datalog.Fact;
 import com.clevercloud.biscuit.datalog.RunLimits;
 import com.clevercloud.biscuit.datalog.SymbolTable;
 import com.clevercloud.biscuit.error.Error;
@@ -12,7 +10,6 @@
 import com.clevercloud.biscuit.error.LogicError;
 import com.clevercloud.biscuit.token.builder.Block;
 
-import io.vavr.Tuple2;
 import io.vavr.control.Option;
 import io.vavr.control.Try;
 
diff --git a/src/test/java/com/clevercloud/biscuit/token/ExampleTest.java b/src/test/java/com/clevercloud/biscuit/token/ExampleTest.java
index 790d55a9..aea687e3 100644
--- a/src/test/java/com/clevercloud/biscuit/token/ExampleTest.java
+++ b/src/test/java/com/clevercloud/biscuit/token/ExampleTest.java
@@ -1,22 +1,12 @@
 package com.clevercloud.biscuit.token;
 
 import com.clevercloud.biscuit.crypto.KeyPair;
-import com.clevercloud.biscuit.datalog.AuthorizedWorld;
 import com.clevercloud.biscuit.error.Error;
-import com.clevercloud.biscuit.error.LogicError;
 import com.clevercloud.biscuit.token.builder.Block;
-import com.clevercloud.biscuit.token.builder.Fact;
-import com.clevercloud.biscuit.token.builder.parser.Parser;
-import io.vavr.Tuple2;
-import io.vavr.control.Either;
 
 import java.security.InvalidKeyException;
 import java.security.NoSuchAlgorithmException;
-import java.security.SecureRandom;
 import java.security.SignatureException;
-import java.util.Set;
-
-import static io.vavr.API.Left;
 
 /* example code for the documentation at https://www.biscuitsec.org
  * if these functions change, please send a PR to update them at https://github.com/biscuit-auth/website
diff --git a/src/test/java/com/clevercloud/biscuit/token/SamplesJsonV2Test.java b/src/test/java/com/clevercloud/biscuit/token/SamplesJsonV2Test.java
index 7e42990e..8e172db5 100644
--- a/src/test/java/com/clevercloud/biscuit/token/SamplesJsonV2Test.java
+++ b/src/test/java/com/clevercloud/biscuit/token/SamplesJsonV2Test.java
@@ -3,13 +3,11 @@
 import biscuit.format.schema.Schema;
 import com.clevercloud.biscuit.crypto.KeyPair;
 import com.clevercloud.biscuit.crypto.PublicKey;
-import com.clevercloud.biscuit.datalog.AuthorizedWorld;
 import com.clevercloud.biscuit.datalog.RunLimits;
 import com.clevercloud.biscuit.error.Error;
 import com.google.gson.Gson;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
-import io.vavr.Tuple2;
 import io.vavr.control.Either;
 import io.vavr.control.Try;
 import org.junit.jupiter.api.DynamicTest;
diff --git a/src/test/java/com/clevercloud/biscuit/token/SamplesV2Test.java b/src/test/java/com/clevercloud/biscuit/token/SamplesV2Test.java
index de96809c..1a20ce65 100644
--- a/src/test/java/com/clevercloud/biscuit/token/SamplesV2Test.java
+++ b/src/test/java/com/clevercloud/biscuit/token/SamplesV2Test.java
@@ -2,14 +2,12 @@
 
 import biscuit.format.schema.Schema;
 import com.clevercloud.biscuit.crypto.PublicKey;
-import com.clevercloud.biscuit.datalog.AuthorizedWorld;
 import com.clevercloud.biscuit.datalog.RunLimits;
 import com.clevercloud.biscuit.error.Error;
 import com.clevercloud.biscuit.error.FailedCheck;
 import com.clevercloud.biscuit.error.LogicError;
 import com.clevercloud.biscuit.token.builder.Check;
 import com.clevercloud.biscuit.token.builder.Rule;
-import io.vavr.Tuple2;
 import io.vavr.control.Try;
 
 import org.junit.jupiter.api.Test;
@@ -28,7 +26,6 @@
 
 import static com.clevercloud.biscuit.crypto.TokenSignature.fromHex;
 import static com.clevercloud.biscuit.token.builder.Utils.*;
-import static io.vavr.API.Right;
 
 
 public class SamplesV2Test {