diff --git a/src/typecode/contenttype.py b/src/typecode/contenttype.py
index f23094b..7c2316a 100644
--- a/src/typecode/contenttype.py
+++ b/src/typecode/contenttype.py
@@ -205,6 +205,12 @@ class Type(object):
         "is_filesystem",
         "is_java_class",
         "is_java_source",
+        "is_julia_source",
+        "is_python_source",
+        "is_javascript_source",
+        "is_cpp_source",
+        "is_rust_source",
+        "is_go_source",
         "is_media",
         "is_media_with_meta",
         "is_office_doc",
@@ -742,7 +748,18 @@ def is_source(self):
         elif self.is_makefile or self.is_js_map:
             return False
 
-        elif self.is_java_source is True or self.is_c_source is True:
+        # Recognize "known-by-extension" source types
+        elif (
+            self.is_java_source or 
+            self.is_c_source or 
+            self.is_julia_source or
+            self.is_python_source or
+            self.is_javascript_source or
+            self.is_cpp_source or
+            self.is_rust_source or
+            self.is_go_source
+        
+        ):
             return True
 
         elif self.filetype_pygment or self.is_script is True:
@@ -758,9 +775,39 @@ def programming_language(self):
         string.
         """
         if self.is_source:
+            # If the custom extension check found Julia, use that name explicitly
+            if self.is_julia_source:
+                return "Julia"
             return self.filetype_pygment or ""
         return ""
 
+    @property
+    def is_julia_source(self):
+        """
+        Return True if the file is Julia source code based on .jl extension.
+        """
+        return self.is_file and self.location.lower().endswith(".jl")
+
+    @property
+    def is_python_source(self):
+        return self.is_file and self.file_name.lower().endswith(('.py', '.pyw'))
+
+    @property
+    def is_javascript_source(self):
+        return self.is_file and self.file_name.lower().endswith(('.js', '.mjs'))
+
+    @property
+    def is_cpp_source(self):
+        return self.is_file and self.file_name.lower().endswith(('.cpp', '.cc', '.cxx', '.hpp'))
+
+    @property
+    def is_rust_source(self):
+        return self.is_file and self.file_name.lower().endswith('.rs')
+
+    @property
+    def is_go_source(self):
+        return self.is_file and self.file_name.lower().endswith('.go')
+
     @property
     def is_c_source(self):
         C_EXTENSIONS = set(
@@ -950,7 +997,8 @@ def get_text_file_start(location, length=4096):
         with open(location, "rb") as f:
             content = text.as_unicode(f.read(length))
     finally:
-        return content
+        pass
+    return content
 
 
 def get_filetype(location):
diff --git a/tests/test_contenttype.py b/tests/test_contenttype.py
index 07fefba..f293b45 100644
--- a/tests/test_contenttype.py
+++ b/tests/test_contenttype.py
@@ -238,6 +238,17 @@ def test_compiled_elf_so_2(self):
         assert get_filetype(test_file) in expected
         assert get_filetype_pygment(test_file) == ""
 
+    def test_programming_language_detection_for_julia(self):
+        # Create a temporary julia file
+        test_file = self.get_temp_file("test.jl")
+        with open(test_file, "w") as f:
+            f.write('println("Hello Julia")')
+
+        # Get the type and check identification
+        T = get_type(test_file)
+        assert is_source(test_file)
+        assert T.programming_language == "Julia"
+
     @pytest.mark.xfail(
         on_mac or on_windows,
         reason="Somehow we get really weird results on macOS with libmagic 5.38 and mac, win32 on libmagic 5.39: "
@@ -407,3 +418,23 @@ def test_size(self):
         test_dir = self.get_test_loc("contenttype/size")
         result = size(test_dir)
         assert result == 18
+
+    def test_contenttype_language_attributes_exist(self):
+        from typecode.contenttype import get_type
+        
+        # Get a Type object to test against using this exact test script
+        test_type = get_type(__file__)
+
+        expected_language_attributes = [
+            'is_c_source',
+            'is_java_source',
+            'is_julia_source',
+            'is_python_source',
+            'is_javascript_source',
+            'is_cpp_source',
+            'is_rust_source',
+            'is_go_source'
+        ]
+
+        for attr_name in expected_language_attributes:
+            assert hasattr(test_type, attr_name), f"ContentType is missing the expected attribute: {attr_name}"