text-splitters[minor]: Added Haskell support in langchain.text_splitter module (#16191)

- **Description:** Haskell language support added in text_splitter
module
  - **Dependencies:** No
  - **Twitter handle:** @nisargtr

If no one reviews your PR within a few days, please @-mention one of
@baskaryan, @eyurtsev, @hwchase17.

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

docs/docs/modules/data_connection/document_transformers/code_splitter.ipynb

@@ -22,7 +22,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 1,
+   "execution_count": 4,
    "id": "a9e37aa1",
    "metadata": {},
    "outputs": [],
@@ -35,7 +35,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 5,
    "id": "e21a2434",
    "metadata": {},
    "outputs": [
@@ -61,10 +61,14 @@
        " 'html',\n",
        " 'sol',\n",
        " 'csharp',\n",
-       " 'cobol']"
+       " 'cobol',\n",
+       " 'c',\n",
+       " 'lua',\n",
+       " 'perl',\n",
+       " 'haskell']"
       ]
      },
-     "execution_count": 2,
+     "execution_count": 5,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -564,13 +568,50 @@
     "c_docs"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "af9de667-230e-4c2a-8c5f-122a28515d97",
+   "metadata": {},
+   "source": [
+    "## Haskell\n",
+    "Here's an example using the Haskell text splitter:"
+   ]
+  },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "id": "688185b5",
    "metadata": {},
-   "outputs": [],
-   "source": []
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[Document(page_content='main :: IO ()'),\n",
+       " Document(page_content='main = do\\n    putStrLn \"Hello, World!\"\\n-- Some'),\n",
+       " Document(page_content='sample functions\\nadd :: Int -> Int -> Int\\nadd x y'),\n",
+       " Document(page_content='= x + y')]"
+      ]
+     },
+     "execution_count": 3,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "HASKELL_CODE = \"\"\"\n",
+    "main :: IO ()\n",
+    "main = do\n",
+    "    putStrLn \"Hello, World!\"\n",
+    "-- Some sample functions\n",
+    "add :: Int -> Int -> Int\n",
+    "add x y = x + y\n",
+    "\"\"\"\n",
+    "haskell_splitter = RecursiveCharacterTextSplitter.from_language(\n",
+    "    language=Language.HASKELL, chunk_size=50, chunk_overlap=0\n",
+    ")\n",
+    "haskell_docs = haskell_splitter.create_documents([HASKELL_CODE])\n",
+    "haskell_docs"
+   ]
   }
  ],
  "metadata": {

libs/text-splitters/langchain_text_splitters/base.py

@@ -291,6 +291,7 @@ class Language(str, Enum):
     C = "c"
     LUA = "lua"
     PERL = "perl"
+    HASKELL = "haskell"
 
 
 @dataclass(frozen=True)

libs/text-splitters/langchain_text_splitters/character.py

@@ -571,7 +571,45 @@ class RecursiveCharacterTextSplitter(TextSplitter):
                 " ",
                 "",
             ]
-
+        elif language == Language.HASKELL:
+            return [
+                # Split along function definitions
+                "\nmain :: ",
+                "\nmain = ",
+                "\nlet ",
+                "\nin ",
+                "\ndo ",
+                "\nwhere ",
+                "\n:: ",
+                "\n= ",
+                # Split along type declarations
+                "\ndata ",
+                "\nnewtype ",
+                "\ntype ",
+                "\n:: ",
+                # Split along module declarations
+                "\nmodule ",
+                # Split along import statements
+                "\nimport ",
+                "\nqualified ",
+                "\nimport qualified ",
+                # Split along typeclass declarations
+                "\nclass ",
+                "\ninstance ",
+                # Split along case expressions
+                "\ncase ",
+                # Split along guards in function definitions
+                "\n| ",
+                # Split along record field declarations
+                "\ndata ",
+                "\n= {",
+                "\n, ",
+                # Split by the normal type of lines
+                "\n\n",
+                "\n",
+                " ",
+                "",
+            ]
         else:
             raise ValueError(
                 f"Language {language} is not supported! "

libs/text-splitters/tests/unit_tests/test_text_splitters.py

@@ -1248,6 +1248,38 @@ def test_solidity_code_splitter() -> None:
     ]
 
 
+def test_haskell_code_splitter() -> None:
+    splitter = RecursiveCharacterTextSplitter.from_language(
+        Language.HASKELL, chunk_size=CHUNK_SIZE, chunk_overlap=0
+    )
+    code = """
+        main :: IO ()
+        main = do
+          putStrLn "Hello, World!"
+
+        -- Some sample functions
+        add :: Int -> Int -> Int
+        add x y = x + y
+    """
+    # Adjusted expected chunks to account for indentation and newlines
+    expected_chunks = [
+        "main ::",
+        "IO ()",
+        "main = do",
+        "putStrLn",
+        '"Hello, World!"',
+        "--",
+        "Some sample",
+        "functions",
+        "add :: Int ->",
+        "Int -> Int",
+        "add x y = x",
+        "+ y",
+    ]
+    chunks = splitter.split_text(code)
+    assert chunks == expected_chunks
+
+
 @pytest.mark.requires("lxml")
 def test_html_header_text_splitter(tmp_path: Path) -> None:
     splitter = HTMLHeaderTextSplitter(