Added a strict equality for types, corrected the `toString` method

src/main/java/fr/insarennes/nperier/minichamo/language/typing/BuiltinType.java

@@ -21,7 +21,7 @@ public class BuiltinType extends Type {
         BUILTIN_TYPES.put(TokenType.TYPE_LIST,   new BuiltinType("list", 1));
     }
 
-    private BuiltinType(String n) {
+    public BuiltinType(String n) {
         super(n);
     }
 
@@ -29,7 +29,7 @@ public class BuiltinType extends Type {
         super(n, arity);
     }
 
-    private BuiltinType(String n, Type[] sp) {
+    public BuiltinType(String n, Type[] sp) {
         super(n, sp);
     }
 

src/main/java/fr/insarennes/nperier/minichamo/language/typing/FunctionType.java

@@ -3,6 +3,7 @@ package fr.insarennes.nperier.minichamo.language.typing;
 import fr.insarennes.nperier.minichamo.utils.ParsingException;
 
 import java.util.Arrays;
+import java.util.List;
 
 public class FunctionType extends Type {
 
@@ -13,6 +14,13 @@ public class FunctionType extends Type {
         }
     }
 
+    public FunctionType(List<Type> sp) {
+        super("function", sp);
+        if(sp.size() < 2) {
+            throw new ParsingException("A function must have at least two elements, found " + sp.size());
+        }
+    }
+
     public Type[] getArgumentTypes() {
         Type[] res = new Type[getArity() - 1];
         for(int i = 0; i < res.length; i++) {

src/main/java/fr/insarennes/nperier/minichamo/language/typing/Type.java

@@ -61,18 +61,37 @@ public abstract class Type {
 
     public abstract Type specify(Type[] sp);
 
+    @Override
+    public boolean equals(Object o) {
+        if(!getClass().equals(o.getClass())) {
+            return false;
+        }
+        Type t = (Type) o;
+        if(!(t.name.equals(name) && t.getArity() == getArity())) {
+            return false;
+        }
+        for(int i = 0; i < specifics.length; i++) {
+            if(!specifics[i].equals(t.specifics[i])) {
+                return false;
+            }
+        }
+        return true;
+    }
+
     @Override
     public String toString() {
         if(!isComplex()) {
             return name;
         }
         StringBuilder builder = new StringBuilder();
-        for(Type t: specifics) {
-            if(t.isComplex()) {
-                builder.append("(").append(t.toString()).append(") ");
-            } else {
-                builder.append(t.toString()).append(" ");
+        if(specifics.length == 1 && ! specifics[0].isComplex()) {
+            builder.append(specifics[0]).append(" ");
+        } else {
+            builder.append("(").append(specifics[0]);
+            for(int i = 1; i < specifics.length; i++) {
+                builder.append(", ").append(specifics[i]);
             }
+            builder.append(") ");
         }
         builder.append(name);
         return builder.toString();