Create DSL patterns (folder/readme)

Pattern: get the top of the column of air

.gitignore

@@ -19,3 +19,7 @@ tmp_*/
 
 # Docs are auto-build. See .github/workflows/gh_pages_doc.yml
 docs
+
+# gt4py/dace caches
+.gt_cache_*
+.dacecache*

dsl_patterns/Do__get_top_of_the_column.py

@@ -0,0 +1,68 @@
+""" Get the top/bottom of the column of air in a stencil
+
+Last update: 2024/07/24
+Description: gt4py doesn't allow for direct indexing in K while doing relative indexing in the
+    other cartesian dimensions. To be able to get the top/bottom of the column of air, we can
+    rely on the `interval` and `temporary` generation features.
+Fortran equivalent:
+```fortran
+do L=1,LM
+  do J=1,JM
+   do I=1,IM
+      ...
+      Field(i,j,LM)
+      ...
+```
+as seen in  https://github.com/GEOS-ESM/GEOSgcm_GridComp/blob/db55c301840d98b788b0e17045510af726c0f555/GEOSagcm_GridComp/GEOSphysics_GridComp/GEOSmoist_GridComp/GEOS_GFDL_1M_InterfaceMod.F90#L603
+"""
+
+from gt4py.cartesian.gtscript import computation, interval, PARALLEL, FORWARD
+from ndsl.boilerplate import get_factories_single_tile_orchestrated_cpu
+from ndsl.constants import X_DIM, Y_DIM, Z_DIM
+from ndsl.dsl.typing import FloatField, FloatFieldIJ
+from ndsl import StencilFactory, QuantityFactory, orchestrate
+import numpy as np
+
+domain = (3, 3, 4)
+
+stcil_fctry, ijk_qty_fctry = get_factories_single_tile_orchestrated_cpu(
+    domain[0], domain[1], domain[2], 0
+)
+
+
+def stencil(PLEmb: FloatField, PLEmb_top: FloatFieldIJ, out_field: FloatField):
+    with computation(FORWARD), interval(-1, None):
+        PLEmb_top = PLEmb
+
+    with computation(PARALLEL), interval(...):
+        out_field = PLEmb_top
+
+
+class Code:
+    def __init__(
+        self,
+        stencil_factory: StencilFactory,
+        qty_fctry: QuantityFactory,
+    ):
+        orchestrate(obj=self, config=stencil_factory.config.dace_config)
+        self._tmp = qty_fctry.zeros([X_DIM, Y_DIM], "n/a")
+        self.stencil = stcil_fctry.from_dims_halo(
+            func=stencil,
+            compute_dims=[X_DIM, Y_DIM, Z_DIM],
+        )
+
+    def __call__(self, PLEmb: FloatField, out_field: FloatField):
+        self.stencil(PLEmb, self._tmp, out_field)
+
+
+if __name__ == "__main__":
+    I = np.ones(domain[0] * domain[1] * domain[2], dtype=np.float64).reshape(domain)
+    I[:, :, domain[2] - 1] = 42
+    O = np.zeros(domain)
+
+    code = Code(stcil_fctry, ijk_qty_fctry)
+    code(I, O)
+
+    print(f"Input:\n{I}\n")
+    print(f"Output:\n{O}\n")
+    assert np.all(O == 42)

dsl_patterns/README.md

@@ -0,0 +1,19 @@
+# DSL Patterns
+
+A repository of small self-contained examples to demonstrate how to write different algorithmics patterns under DSL or document failure to port such patterns (and eventually the workarounds)
+
+The folder should remain as flat as possible and each file should follow the naming pattern: [Do/Dont/Cant/WIP]_[DescriptiveName].py, with:
+
+ - `Do`: the stack knows how to handle this pattern in a satisfactory way for now. No work planned.
+ - `Dont`: the stack _disallows_ this pattern. Provide a _why_, an expected error example and potentially a workaround when applicable.
+ - `Cant`: the stack lacks the feature to handle this case. Show the Numpy/Python workaround.
+ - `WIP`: a workaround exist but is unsatisfactory. Show said workaround.
+
+Then the top of the file should have a docstrings with:
+
+ - Date last updated
+ - Ticket link (if applicable)
+ - Description of the pattern
+ - Original Fortran code (if applicable)
+ - Performance related explanation (if applicable)
+