Experimental: set the language lexer only

if the language_info is preserved in the filtered metadata

CHANGELOG.md

@@ -6,6 +6,7 @@ Jupytext ChangeLog
 
 **Changed**
 - We have updated the JupyterLab extension dependencies ([#1300](https://github.com/mwouts/jupytext/pull/1300)). Thanks to [Mahendra Paipuri](https://github.com/mahendrapaipuri) for this PR!
+- The language lexer (e.g. `ipython3`) for `md:myst` files is now only included when `language_info` is added to `notebook_metadata_filter`.
 
 
 1.16.7 (2025-02-09)

src/jupytext/compare.py

@@ -394,12 +394,14 @@ def test_round_trip_conversion(
 
 
 # The functions below are used in the Jupytext text collection
-def create_mirror_file_if_missing(mirror_file, notebook, fmt):
+def create_mirror_file_if_missing(mirror_file, notebook, fmt, config):
     if not os.path.isfile(mirror_file):
-        write(notebook, mirror_file, fmt=fmt)
+        write(notebook, mirror_file, fmt=fmt, config=config)
 
 
-def assert_conversion_same_as_mirror(nb_file, fmt, mirror_name, compare_notebook=False):
+def assert_conversion_same_as_mirror(
+    nb_file, fmt, mirror_name, compare_notebook=False, config=None
+):
     """This function is used in the tests"""
     dirname, basename = os.path.split(nb_file)
     file_name, org_ext = os.path.splitext(basename)
@@ -414,25 +416,25 @@ def assert_conversion_same_as_mirror(nb_file, fmt, mirror_name, compare_notebook
     # it's better not to have Jupytext metadata in test notebooks:
     if fmt == "ipynb" and "jupytext" in notebook.metadata:  # pragma: no cover
         notebook.metadata.pop("jupytext")
-        write(nb_file, fmt=fmt)
+        write(nb_file, fmt=fmt, config=config)
 
-    create_mirror_file_if_missing(mirror_file, notebook, fmt)
+    create_mirror_file_if_missing(mirror_file, notebook, fmt, config=config)
 
     # Compare the text representation of the two notebooks
     if compare_notebook:
         # Read and convert the mirror file to the latest nbformat version if necessary
-        nb_mirror = read(mirror_file, as_version=notebook.nbformat)
+        nb_mirror = read(mirror_file, as_version=notebook.nbformat, config=config)
         nb_mirror.nbformat_minor = notebook.nbformat_minor
         compare_notebooks(nb_mirror, notebook)
         return
     elif ext == ".ipynb":
-        notebook = read(mirror_file)
+        notebook = read(mirror_file, config=config)
         fmt.update({"extension": org_ext})
-        actual = writes(notebook, fmt)
+        actual = writes(notebook, fmt, config=config)
         with open(nb_file, encoding="utf-8") as fp:
             expected = fp.read()
     else:
-        actual = writes(notebook, fmt)
+        actual = writes(notebook, fmt, config=config)
         with open(mirror_file, encoding="utf-8") as fp:
             expected = fp.read()
 
@@ -442,8 +444,8 @@ def assert_conversion_same_as_mirror(nb_file, fmt, mirror_name, compare_notebook
 
     # Compare the two notebooks
     if ext != ".ipynb":
-        notebook = read(nb_file)
-        nb_mirror = read(mirror_file, fmt=fmt)
+        notebook = read(nb_file, config=config)
+        nb_mirror = read(mirror_file, fmt=fmt, config=config)
 
         if fmt.get("format_name") == "sphinx":
             nb_mirror.cells = nb_mirror.cells[1:]

src/jupytext/jupytext.py

@@ -232,12 +232,8 @@ def writes(self, nb, metadata=None, **kwargs):
         if self.fmt.get(
             "format_name"
         ) == MYST_FORMAT_NAME or self.ext in myst_extensions(no_md=True):
-            pygments_lexer = metadata.get("language_info", {}).get(
-                "pygments_lexer", None
-            )
             return notebook_to_myst(
                 self.filter_notebook(nb, metadata),
-                default_lexer=pygments_lexer,
             )
 
         # Copy the notebook, in order to be sure we do not modify the original notebook

tests/data/notebooks/outputs/ipynb_to_myst/Line_breaks_in_LateX_305.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.7.4
 ---
 
 This cell uses no particular cell marker

tests/data/notebooks/outputs/ipynb_to_myst/Notebook with function and cell metadata 164.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.6.6
 ---
 
 ```{code-cell} ipython3

tests/data/notebooks/outputs/ipynb_to_myst/Notebook with html and latex cells.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.6.6
 ---
 
 ```{code-cell} ipython3

tests/data/notebooks/outputs/ipynb_to_myst/Notebook with many hash signs.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.6.6
 ---
 
 ##################################################################

tests/data/notebooks/outputs/ipynb_to_myst/Notebook with metadata and long cells.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.6.6
 ---
 
 # Part one - various cells

tests/data/notebooks/outputs/ipynb_to_myst/Notebook_with_R_magic.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 2
   language: python
   name: python2
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 2
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython2
+  version: 2.7.11
 ---
 
 # A notebook with R cells

tests/data/notebooks/outputs/ipynb_to_myst/Notebook_with_more_R_magic_111.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.6.6
 ---
 
 ```{code-cell} ipython3

tests/data/notebooks/outputs/ipynb_to_myst/R notebook with invalid cell keys.md

@@ -3,6 +3,13 @@ kernelspec:
   display_name: R
   language: R
   name: ir
+language_info:
+  codemirror_mode: r
+  file_extension: .r
+  mimetype: text/x-r-source
+  name: R
+  pygments_lexer: r
+  version: 3.5.1
 ---
 
 This notebook was created with IRKernel 0.8.12, and is not completely valid, as the code cell below contains an unexpected 'source' entry. This did cause https://github.com/mwouts/jupytext/issues/234. Note that the problem is solved when one upgrades to IRKernel 1.0.0.

tests/data/notebooks/outputs/ipynb_to_myst/Reference Guide for Calysto Scheme.md

@@ -3,6 +3,12 @@ kernelspec:
   display_name: Calysto Scheme (Python)
   language: scheme
   name: calysto_scheme
+language_info:
+  codemirror_mode:
+    name: scheme
+  mimetype: text/x-scheme
+  name: scheme
+  pygments_lexer: scheme
 ---
 
 <img src="images/logo-64x64.png"/>

tests/data/notebooks/outputs/ipynb_to_myst/The flavors of raw cells.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.7.3
 ---
 
 ```{raw-cell}

tests/data/notebooks/outputs/ipynb_to_myst/cat_variable.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.6.4
 ---
 
 ```{code-cell} ipython3

tests/data/notebooks/outputs/ipynb_to_myst/coconut_homepage_demo.md

@@ -3,6 +3,15 @@ kernelspec:
   display_name: Coconut
   language: coconut
   name: coconut
+language_info:
+  codemirror_mode:
+    name: python
+    version: 3
+  file_extension: .coco
+  mimetype: text/x-python3
+  name: coconut
+  pygments_lexer: coconut
+  version: 1.4.3-post_dev25
 ---
 
 Taken from [coconut-lang.org](coconut-lang.org)

tests/data/notebooks/outputs/ipynb_to_myst/convert_to_py_then_test_with_update83.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.5.3
 ---
 
 ```{code-cell} ipython3

tests/data/notebooks/outputs/ipynb_to_myst/csharp.md

@@ -3,6 +3,12 @@ kernelspec:
   display_name: .NET (C#)
   language: C#
   name: .net-csharp
+language_info:
+  file_extension: .cs
+  mimetype: text/x-csharp
+  name: C#
+  pygments_lexer: csharp
+  version: '8.0'
 ---
 
 We start with...

tests/data/notebooks/outputs/ipynb_to_myst/demo_gdl_fbp.md

@@ -3,6 +3,11 @@ kernelspec:
   display_name: IDL [conda env:gdl] *
   language: IDL
   name: conda-env-gdl-idl
+language_info:
+  codemirror_mode: idl
+  file_extension: .pro
+  mimetype: text/x-idl
+  name: idl
 ---
 
 ## GDL demo notebook

tests/data/notebooks/outputs/ipynb_to_myst/evcxr_jupyter_tour.md

@@ -3,6 +3,13 @@ kernelspec:
   display_name: Rust
   language: rust
   name: rust
+language_info:
+  codemirror_mode: rust
+  file_extension: .rs
+  mimetype: text/rust
+  name: Rust
+  pygment_lexer: rust
+  version: ''
 ---
 
 # Tour of the EvCxR Jupyter Kernel

tests/data/notebooks/outputs/ipynb_to_myst/frozen_cell.md

@@ -3,6 +3,16 @@ kernelspec:
   display_name: Python 3
   language: python
   name: python3
+language_info:
+  codemirror_mode:
+    name: ipython
+    version: 3
+  file_extension: .py
+  mimetype: text/x-python
+  name: python
+  nbconvert_exporter: python
+  pygments_lexer: ipython3
+  version: 3.7.0
 ---
 
 ```{code-cell} ipython3

tests/data/notebooks/outputs/ipynb_to_myst/fsharp.md

@@ -3,6 +3,12 @@ kernelspec:
   display_name: .NET (F#)
   language: F#
   name: .net-fsharp
+language_info:
+  file_extension: .fs
+  mimetype: text/x-fsharp
+  name: C#
+  pygments_lexer: fsharp
+  version: '4.5'
 ---
 
 This notebook was inspired by [Plottting with XPlot](https://github.com/dotnet/interactive/blob/master/NotebookExamples/fsharp/Docs/Plotting%20with%20Xplot.ipynb).

tests/data/notebooks/outputs/ipynb_to_myst/gnuplot_notebook.md

@@ -3,6 +3,14 @@ kernelspec:
   display_name: gnuplot
   language: gnuplot
   name: gnuplot
+language_info:
+  codemirror_mode: Octave
+  file_extension: .gp
+  help_links:
+  - text: MetaKernel Magics
+    url: https://metakernel.readthedocs.io/en/latest/source/README.html
+  mimetype: text/x-gnuplot
+  name: gnuplot
 ---
 
 # Sample gnuplot notebook

tests/data/notebooks/outputs/ipynb_to_myst/haskell_notebook.md

@@ -3,6 +3,13 @@ kernelspec:
   display_name: Haskell
   language: haskell
   name: haskell
+language_info:
+  codemirror_mode: ihaskell
+  file_extension: .hs
+  mimetype: text/x-haskell
+  name: haskell
+  pygments_lexer: Haskell
+  version: 8.10.7
 ---
 
 # Example Haskell Notebook