Updating of loopy make `python -c "import firedrake"` failed

[lrtfm]

The command raises the error "ImportError: cannot import name 'CachedCombineMapper' from 'pymbolic.mapper' ". It seems that the new version loopy needs the develop version py-pymbolic and the package py-immutables.

Traceback after install firedrake:

[firedrake-real-int32] [z2yang@ws2 firedrake-real-int32]$ python -c "import firedrake"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/firedrake/__init__.py", line 69, in <module>
    from pyop2 import op2                        # noqa: F401
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/pyop2/__init__.py", line 4, in <module>
    from pyop2.op2 import *  # noqa
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/pyop2/op2.py", line 38, in <module>
    from pyop2.configuration import configuration
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/pyop2/configuration.py", line 38, in <module>
    from loopy.target.c import CWithGNULibcTarget
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/loopy/__init__.py", line 24, in <module>
    from loopy.symbolic import (
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/loopy/symbolic.py", line 43, in <module>
    from pymbolic.mapper import (
ImportError: cannot import name 'CachedCombineMapper' from 'pymbolic.mapper' (/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/pymbolic/mapper/__init__.py)

Traceback after installing py-pymbolic@develop:

[firedrake-real-int32] [z2yang@ws2 firedrake-real-int32]$ python -c "import firedrake"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/firedrake/__init__.py", line 69, in <module>
    from pyop2 import op2                        # noqa: F401
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/pyop2/__init__.py", line 4, in <module>
    from pyop2.op2 import *  # noqa
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/pyop2/op2.py", line 38, in <module>
    from pyop2.configuration import configuration
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/pyop2/configuration.py", line 38, in <module>
    from loopy.target.c import CWithGNULibcTarget
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/loopy/__init__.py", line 24, in <module>
    from loopy.symbolic import (
  File "/home/z2yang/opt/firedrake-real-int32/.spack-env/view/lib/python3.10/site-packages/loopy/symbolic.py", line 52, in <module>
    import immutables
ModuleNotFoundError: No module named 'immutables'

[connorjward]

Yes immutables is a new dependency of loopy. I forgot when I updated our loopy branch that spack doesn't respect Python declaring dependencies. A new spack package may be needed.

[lrtfm]

As spack has package py-immutables, we just need to add it as a dependency.