build: drop support for Python 3.6 (#132)

* build: drop support for Python 3.6
* fix: update links to AmpForm API on RTD
* style: rewrite type hints with PEP563
  https://peps.python.org/pep-0563

.cspell.json

@@ -214,6 +214,7 @@
         "pandoc",
         "pcolormesh",
         "pdg's",
+        "phasespace",
         "phsp",
         "pmatrix",
         "preorder",

.github/workflows/requirements-cron.yml

@@ -13,7 +13,6 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-          - "3.6"
           - "3.7"
           - "3.8"
           - "3.9"

.github/workflows/requirements-pr.yml

@@ -36,7 +36,6 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-          - "3.6"
           - "3.7"
           - "3.8"
           - "3.9"

.pre-commit-config.yaml

@@ -99,10 +99,12 @@ repos:
         additional_dependencies:
           - black>=22.1.0
       - id: nbqa-flake8
+        additional_dependencies:
+          - flake8-future-annotations
       - id: nbqa-isort
       - id: nbqa-pyupgrade
         args:
-          - --py36-plus
+          - --py37-plus
 
   - repo: https://github.com/kynan/nbstripout
     rev: 0.5.0
@@ -145,7 +147,7 @@ repos:
     hooks:
       - id: pyupgrade
         args:
-          - --py36-plus
+          - --py37-plus
 
   # The following tools have to be install locally, because they can also be
   # used by code editors (e.g. linting and format-on-save).

docs/adr/001/operators.ipynb

@@ -451,7 +451,7 @@
     "\n",
     "Here's a rough sketch with `tensorwaves` in mind.\n",
     "```python\n",
-    "from typing import Dict, Generator, List\n",
+    "from typing import Generator\n",
     "\n",
     "import attr\n",
     "\n",
@@ -483,18 +483,18 @@
     "\n",
     "    def __init__(self, model: AmplitudeModel) -> None:\n",
     "        self.__model: AmplitudeModel\n",
-    "        self.__parameter_couplings: Dict[str, str]\n",
+    "        self.__parameter_couplings: dict[str, str]\n",
     "\n",
     "    @property\n",
-    "    def parameters(self) -> List[FitParameter]:\n",
+    "    def parameters(self) -> list[FitParameter]:\n",
     "        initial_parameters = list(__yield_parameter(self.__model))\n",
     "        self.__apply_couplings()\n",
     "        return self.__convert(initial_parameters)\n",
     "\n",
     "    def couple_parameters(self, parameter1: str, parameter2: str) -> None:\n",
     "        pass\n",
     "\n",
-    "    def __convert(self, params: List[InitialParameter]) -> List[FitParameter]:\n",
+    "    def __convert(self, params: list[InitialParameter]) -> list[FitParameter]:\n",
     "        pass\n",
     "\n",
     "\n",
@@ -530,7 +530,7 @@
     "builder = IntensityBuilder(kinematics)\n",
     "\n",
     "intensity = builder.create(amp_model)  # this would call amp_model.parameters\n",
-    "parameters: Dict[str, float] = intensity.parameters\n",
+    "parameters: dict[str, float] = intensity.parameters\n",
     "# PROBLEM?: fix status is lost at this point\n",
     "\n",
     "data_sample = generate_data(...)\n",

docs/adr/001/sympy.ipynb

@@ -80,16 +80,16 @@
    },
    "outputs": [],
    "source": [
-    "from typing import Dict\n",
+    "from __future__ import annotations\n",
     "\n",
     "import attr\n",
     "import sympy as sp\n",
     "\n",
     "\n",
     "@attr.s\n",
     "class AmplitudeModel:\n",
-    "    initial_values: Dict[sp.Symbol, float] = attr.ib(default={})\n",
-    "    dynamics: Dict[sp.Symbol, sp.Function] = attr.ib(default={})\n",
+    "    initial_values: dict[sp.Symbol, float] = attr.ib(default={})\n",
+    "    dynamics: dict[sp.Symbol, sp.Function] = attr.ib(default={})\n",
     "    intensity: sp.Expr = attr.ib(default=None)"
    ]
   },

docs/adr/002/composition.ipynb

@@ -62,7 +62,7 @@
    },
    "outputs": [],
    "source": [
-    "from typing import Tuple\n",
+    "from __future__ import annotations\n",
     "\n",
     "import attr\n",
     "import sympy as sp\n",
@@ -94,8 +94,8 @@
    "source": [
     "@attr.s(frozen=True)\n",
     "class DynamicsExpression:\n",
-    "    variables: Tuple[sp.Symbol, ...] = attr.ib()\n",
-    "    parameters: Tuple[sp.Symbol, ...] = attr.ib()\n",
+    "    variables: tuple[sp.Symbol, ...] = attr.ib()\n",
+    "    parameters: tuple[sp.Symbol, ...] = attr.ib()\n",
     "    expression: sp.Expr = attr.ib()\n",
     "\n",
     "    def substitute(self) -> sp.Expr:\n",
@@ -2020,7 +2020,7 @@
    "outputs": [],
    "source": [
     "def expression(\n",
-    "    variables: Tuple[sp.Symbol, ...], parameters: Tuple[sp.Symbol, ...]\n",
+    "    variables: tuple[sp.Symbol, ...], parameters: tuple[sp.Symbol, ...]\n",
     ") -> sp.Expr:\n",
     "    pass"
    ]