chore: prepare for release

Letsql uses maturin as the build-backend. To handle our dependencies
we use poetry. As of now, and in the future, maturin does not recognize
the dependencies specified by poetry see this issue:

PyO3/maturin#632

It also does not provide an alternative way to support dynamic dependencies
The following issue is still open

PyO3/maturin#1537

On the other side poetry will support PEP-621 project style dependencies
in the version 2.0

python-poetry/poetry#3332

Therefore one simple solution is to duplicate the dependencies section, as in
the package:

https://github.com/tmtenbrink/rustfrc/blob/main/pyproject.toml

To do so, a semi-automated approach is to generate the dependencies using poetry
export

poetry export -f requirements.txt --without="test,dev,docs" /
--all-extras --without-hashes --output requirements.txt

And then update the dependencies section in the pyproject.toml file.

Additionally this commit solves a few inconsistencies regarding packages
listed as optional (duckdb, ibis), but when running the code it gives errors.

pyproject.toml

@@ -5,7 +5,27 @@ build-backend = "maturin"
 [project]
 name = "letsql"
 dynamic = ["version"]
+dependencies = [
+    "ibis-framework==9.0.0 ; python_version >= '3.10' and python_version < '4.0'",
+    "dask==2023.12.1 ; python_version >= '3.10' and python_version < '4.0'",
+    "attrs==23.2.0 ; python_version >= '3.10' and python_version < '4.0'",
+    "connectorx==0.3.2 ; python_version >= '3.10' and python_version < '4.0'",
+    "psycopg2-binary==2.9.9 ; python_version >= '3.10' and python_version < '4.0'",
+    "sqlalchemy==2.0.29 ; python_version >= '3.10' and python_version < '4.0'",
+    "pyarrow==13.0.0 ; python_version >= '3.10' and python_version < '4.0'",
+    "palmerpenguins==0.1.4 ; python_version >= '3.10' and python_version < '4.0'",
+    "structlog==24.2.0 ; python_version >= '3.10' and python_version < '4.0'",
+    "pytest-mock==3.14.0 ; python_version >= '3.10' and python_version < '4.0'",
+]
 requires-python = ">=3.7"
+authors = [
+    { name = "Hussain Sultan", email = "hussain@letsql.com" },
+]
+maintainers = [
+    { email = "Dan Lovell <dan@letsql.com>" },
+    { email = "Daniel Mesejo <mesejo@letsql.com>" },
+]
+description = "Data processing library built on top of Ibis and DataFusion to write multi-engine data workflows."
 readme = "README.md"
 license = { file = "LICENSE" }
 classifiers = [
@@ -25,6 +45,18 @@ Repository = "https://github.com/letsql/letsql.git"
 Issues = "https://github.com/letsql/letsql/issues"
 Changelog = "https://github.com/letsql/letsql/blob/main/CHANGELOG.md"
 
+[project.optional-dependencies]
+duckb = [
+    "duckdb==0.10.3 ; python_version >= '3.10' and python_version < '4.0'"
+]
+datafusion = [
+    "datafusion==34.0.0 ; python_version >= '3.10' and python_version < '4.0'"
+]
+snowflake = [
+    "snowflake-connector-python==3.10.1 ; python_version >= '3.10' and python_version < '4.0'"
+]
+
+
 [tool.maturin]
 module-name = "letsql._internal"
 python-source = "python"

python/letsql/backends/let/__init__.py

@@ -9,7 +9,6 @@
 from ibis import BaseBackend
 from ibis.expr import types as ir
 from ibis.expr.schema import SchemaLike
-from ibis.backends.datafusion import Backend as IbisDataFusionBackend
 from sqlglot import exp, parse_one
 
 import letsql.backends.let.hotfix  # noqa: F401
@@ -64,7 +63,10 @@ def register(
                     table_or_expr = self._sources.get_table_or_op(table_or_expr)
                     backend = self._sources.get_backend(table_or_expr)
 
-                if isinstance(backend, (DataFusionBackend, IbisDataFusionBackend)):
+                if (
+                    isinstance(backend, DataFusionBackend)
+                    or getattr(backend, "name", "") == DataFusionBackend.name
+                ):
                     source = _get_datafusion_dataframe(backend, source)
 
         registered_table = super().register(source, table_name=table_name, **kwargs)

python/letsql/common/utils/dask_normalize_expr.py

@@ -5,6 +5,7 @@
 import ibis.expr.operations.relations as ir
 import sqlglot as sg
 
+import letsql
 from letsql.expr.relations import (
     make_native_op,
 )
@@ -18,15 +19,12 @@ def expr_is_bound(expr):
 def unbound_expr_to_default_sql(expr):
     if expr_is_bound(expr):
         raise ValueError
-    default_sql = ibis.to_sql(
-        expr,
-        dialect=ibis.options.sql.default_dialect,
-    )
+    default_sql = letsql.to_sql(expr)
     return str(default_sql)
 
 
 def normalize_memory_databasetable(dt):
-    if dt.source.name not in ("pandas", "datafusion", "duckdb"):
+    if dt.source.name not in ("pandas", "let", "datafusion", "duckdb"):
         raise ValueError
     return dask.base._normalize_seq_func(
         (
@@ -175,7 +173,7 @@ def normalize_backend(con):
         con_details = {k: con_dct[k] for k in ("host", "port", "dbname")}
     elif name == "pandas":
         con_details = id(con.dictionary)
-    elif name in ("datafusion", "duckdb"):
+    elif name in ("datafusion", "duckdb", "let"):
         con_details = id(con.con)
     else:
         raise ValueError

python/letsql/config.py

@@ -84,6 +84,19 @@ class Repr(Config):
     interactive: Interactive = Interactive()
 
 
+class SQL(Config):
+    """SQL-related options.
+
+    Attributes
+    ----------
+    dialect : str
+        Dialect to use for printing SQL when the backend cannot be determined.
+
+    """
+
+    dialect: str = "datafusion"
+
+
 class Options(Config):
     """LETSQL configuration options
 
@@ -100,6 +113,7 @@ class Options(Config):
     cache: Cache = Cache()
     backend: Optional[Any] = None
     repr: Repr = Repr()
+    sql: SQL = SQL()
 
     @property
     def interactive(self) -> bool:

python/letsql/expr/api.py

@@ -13,8 +13,10 @@
 import ibis.expr.schema as sch
 import ibis.expr.types as ir
 from ibis import api
+from ibis.backends.sql.dialects import DataFusion
 from ibis.common.deferred import Deferred, _, deferrable
 from ibis.expr.schema import Schema
+from ibis.expr.sql import SQLString
 from ibis.expr.types import (
     Column,
     DateValue,
@@ -90,6 +92,7 @@
     "table",
     "time",
     "today",
+    "to_sql",
     "timestamp",
     "union",
     "uuid",
@@ -1515,3 +1518,27 @@ def interval(
         microseconds=microseconds,
         nanoseconds=nanoseconds,
     )
+
+
+def to_sql(expr: ir.Expr, pretty: bool = True) -> SQLString:
+    """Return the formatted SQL string for an expression.
+
+    Parameters
+    ----------
+    expr
+        Ibis expression.
+    pretty
+        Whether to use pretty formatting.
+
+    Returns
+    -------
+    str
+        Formatted SQL string
+
+    """
+    from letsql.config import _backend_init
+
+    con = _backend_init()
+    sg_expr = con._to_sqlglot(expr.unbind())
+    sql = sg_expr.sql(dialect=DataFusion, pretty=pretty)
+    return SQLString(sql)