diff --git a/k.krak b/k.krak
index 339fa3b..01660d4 100644
--- a/k.krak
+++ b/k.krak
@@ -175,17 +175,28 @@ fun main(argc: int, argv: **char): int {
             println("trying to unify " + t1->bound_to->to_string() + " and " + t2->bound_to->to_string())
             if (t1->bound_to->equality(t2->bound_to, false) || t1->bound_to->is_unknown())
                 t1->set(t2->bound_to)
-            else
+            else if (t2->bound_to->is_unknown())
                 t2->set(t1->bound_to)
+            else
+                error("Doesn't typecheck! Attempted to unify " + t1->bound_to->to_string() + " and " + t2->bound_to->to_string())
         }
         var traverse_for_unify: fun(*tree<ast>): void = fun(t: *tree<ast>) {
             t->children.for_each(traverse_for_unify)
             match (t->data) {
                 ast::_declaration() if (t->children.size > 1)
                                         unify(get_type(t->children[0]), get_type(t->children[1]))
-                /*ast::_assignment()*/
-                /*ast::_call()*/
-                /*ast::_return()*/
+                /*ast::_assignment()   unify(get_type(t->children[0]), get_type(t->children[1]))*/
+                ast::_call() {
+                    var fun_type = get_type(t->children[0])->bound_to
+                    if (!fun_type->is_fun())
+                        error("trying to call not a function type: " + fun_type->to_string())
+                    if (fun_type->base._fun.first.first.size != (t->children.size - 1))
+                        error("trying to call function with type wrong number of params (" + to_string(fun_type->base._fun.first.first.size) + " vs " + to_string(t->children.size - 1) + "): " + fun_type->to_string())
+                    for (var i = 1; i < t->children.size; i++;)
+                        unify(fun_type->base._fun.first.first[i-1], get_type(t->children[i]))
+                }
+                ast::_return() if (t->children.size > 0)
+                                   unify(get_type(get_ancestor_satisfying(t, fun(t: *tree<ast>): bool return is_function(t);))->bound_to->base._fun.first.second, get_type(t->children[0]))
             }
         }
         traverse_for_unify(item)
@@ -590,9 +601,13 @@ fun syntax_to_ast(file_name: str, syntax: *tree<symbol>, import_paths: ref vec<s
                                  syntax_to_ast_helper(syntax->children[0]),
                                  syntax_to_ast_helper(syntax->children[2])))
             }
-        } else if (syntax->data.name == "number")
-            return _value(concat(syntax), binding(type(base_type::_int(), 0, false)))
-        else if (syntax->data.name == "bool")
+        } else if (syntax->data.name == "number") {
+            var number_string = concat(syntax)
+            if (number_string.contains('.'))
+                return _value(number_string, binding(type(base_type::_double(), 0, false)))
+            else
+                return _value(number_string, binding(type(base_type::_int(), 0, false)))
+        } else if (syntax->data.name == "bool")
             return _value(concat(syntax), binding(type(base_type::_bool(), 0, false)))
         else if (syntax->data.name == "scoped_identifier" || syntax->data.name == "identifier")
             return make_ast_binding(concat(syntax))
diff --git a/stdlib/ast.krak b/stdlib/ast.krak
index e7d02c4..f078fad 100644
--- a/stdlib/ast.krak
+++ b/stdlib/ast.krak
@@ -37,7 +37,7 @@ fun get_type(a: *tree<ast>): *binding<type> {
         ast::_identifier(b)         return b.second
         ast::_binding(b)            return get_type(b.second->bound_to)
         ast::_function(b)           return b.second
-        /*ast::_call()                return get_type(a->children[0])->bound_to->base->_fun->second*/
+        ast::_call()                return get_type(a->children[0])->bound_to->base._fun.first.second
         /*ast::_compiler_intrinsic(b) return str("_compiler_intrinsic(") + b.first + ")"*/
         ast::_cast(b)               return b
         ast::_value(b)              return b.second
@@ -249,6 +249,13 @@ fun is_value(i: *tree<ast>): bool { match(i->data) { ast::_value(b) return true;
 
 fun is_top_level_item(i: *tree<ast>): bool { return i->parent != null<tree<ast>>() && is_translation_unit(i->parent); }
 
+fun get_ancestor_satisfying(t: *tree<ast>, p: fun(*tree<ast>): bool): *tree<ast> {
+    t = t->parent
+    while (t != null<tree<ast>>() && !p(t))
+        t = t->parent
+    return t
+}
+
 
 var bindings: *vec<*void>
 
diff --git a/stdlib/str.krak b/stdlib/str.krak
index 20278d4..16fd3a2 100644
--- a/stdlib/str.krak
+++ b/stdlib/str.krak
@@ -309,5 +309,8 @@ obj str (Object, Serializable, Hashable) {
     fun for_each(func: fun(char):void) {
         data.for_each(func)
     }
+    fun contains(c: char): bool {
+        return data.contains(c)
+    }
 };