First pass at adding a language mode for elixir (#1571)

I am not an elixir expert but I think this covers the basics. I wasn't
able to find an elixir example in community forks so I put this together
on my own.

When this gets merged I will be on the lookout for feedback to improve
it incrementally in subsequent changes.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Phil Cohen <[email protected]>

core/file_extension/file_extension.py

@@ -7,6 +7,7 @@
 
 _file_extensions_defaults = {
     "dot pie": ".py",
+    "dot elixir": ".ex",
     "dot talon": ".talon",
     "dot mark down": ".md",
     "dot shell": ".sh",

core/modes/language_modes.py

@@ -20,6 +20,7 @@
     "javascript": "js",
     "javascriptreact": "jsx",
     # "json": "json",
+    "elixir": "ex",
     "kotlin": "kt",
     "lua": "lua",
     "markdown": "md",

lang/elixir/elixir.py

@@ -0,0 +1,168 @@
+from talon import Context, Module, actions, settings
+
+ctx = Context()
+mod = Module()
+ctx.matches = r"""
+code.language: elixir
+"""
+
+# Elixir keywords and constructs
+ctx.lists["user.code_keyword"] = {
+    "def": "def ",
+    "def p": "defp ",
+    "def module": "defmodule ",
+    "do": "do ",
+    "end": "end",
+    "if": "if ",
+    "else": "else ",
+    "cond": "cond ",
+    "case": "case ",
+    "when": "when ",
+    "f n": "fn ",
+    "receive": "receive ",
+    "after": "after ",
+    "try": "try ",
+    "catch": "catch ",
+    "rescue": "rescue ",
+    "raise": "raise ",
+    "with": "with ",
+    "unless": "unless ",
+    "import": "import ",
+    "alias": "alias ",
+    "require": "require ",
+    "use": "use ",
+}
+
+
+@ctx.action_class("user")
+class UserActions:
+    def code_comment_line_prefix():
+        actions.insert("# ")
+
+    def code_operator_lambda():
+        actions.auto_insert("->")
+
+    def code_operator_assignment():
+        actions.auto_insert(" = ")
+
+    def code_operator_addition():
+        actions.auto_insert(" + ")
+
+    def code_operator_subtraction():
+        actions.auto_insert(" - ")
+
+    def code_operator_multiplication():
+        actions.auto_insert(" * ")
+
+    def code_operator_division():
+        actions.auto_insert(" / ")
+
+    def code_operator_equal():
+        actions.auto_insert(" == ")
+
+    def code_operator_not_equal():
+        actions.auto_insert(" != ")
+
+    def code_operator_greater_than():
+        actions.auto_insert(" > ")
+
+    def code_operator_greater_than_or_equal_to():
+        actions.auto_insert(" >= ")
+
+    def code_operator_less_than():
+        actions.auto_insert(" < ")
+
+    def code_operator_less_than_or_equal_to():
+        actions.auto_insert(" <= ")
+
+    def code_operator_and():
+        actions.auto_insert(" and ")
+
+    def code_operator_or():
+        actions.auto_insert(" or ")
+
+    def code_self():
+        actions.auto_insert("self")
+
+    def code_insert_true():
+        actions.auto_insert("true")
+
+    def code_insert_false():
+        actions.auto_insert("false")
+
+    def code_insert_null():
+        actions.insert("nil")
+
+    def code_insert_is_null():
+        actions.insert(" == nil")
+
+    def code_insert_is_not_null():
+        actions.insert(" != nil")
+
+    def code_state_if():
+        actions.user.insert_between("if ", " do\nend")
+
+    def code_state_else_if():
+        actions.user.insert_between("else if ", " do\nend")
+
+    def code_state_else():
+        actions.insert("else\nend")
+        actions.key("enter")
+
+    def code_state_case():
+        actions.user.insert_between("case ", " do\nend")
+
+    def code_state_for():
+        actions.user.insert_between("for ", " do\nend")
+
+    def code_state_while():
+        actions.user.insert_between("while ", " do\nend")
+
+    def code_define_class():
+        # Elixir doesn't have classes, so this is not applicable
+        pass
+
+    def code_state_return():
+        # Elixir functions automatically return the last evaluated expression
+        pass
+
+    def code_insert_function(text: str, selection: str):
+        text += f"({selection or ''})"
+        actions.user.paste(text)
+        actions.edit.left()
+
+    def code_default_function(text: str):
+        result = "def {}".format(
+            actions.user.formatted_text(
+                text, settings.get("user.code_protected_function_formatter")
+            )
+        )
+        actions.user.code_insert_function(result, None)
+
+    def code_public_function(text: str):
+        actions.user.code_default_function(text)
+
+    def code_private_function(text: str):
+        """Inserts private function declaration"""
+        result = "defp {}".format(
+            actions.user.formatted_text(
+                text, settings.get("user.code_private_function_formatter")
+            )
+        )
+        actions.user.code_insert_function(result, None)
+
+    def code_import_module(text: str):
+        actions.auto_insert("import ")
+        actions.insert(text)
+
+    def code_alias_module(text: str):
+        actions.auto_insert("alias ")
+        actions.insert(text)
+
+    def code_require_module(text: str):
+        actions.auto_insert("require ")
+        actions.insert(text)
+
+    def code_use_module(text: str):
+        actions.auto_insert("use ")
+        actions.insert(text)

lang/elixir/elixir.talon

@@ -0,0 +1,40 @@
+code.language: elixir
+-
+tag(): user.code_functional
+tag(): user.code_concurrent
+
+tag(): user.code_comment_line
+tag(): user.code_data_bool
+tag(): user.code_data_null
+tag(): user.code_functions
+tag(): user.code_keywords
+tag(): user.code_libraries
+tag(): user.code_operators_array
+tag(): user.code_operators_assignment
+tag(): user.code_operators_math
+tag(): user.code_operators_lambda
+
+settings():
+    user.code_private_function_formatter = "snake_case"
+    user.code_public_function_formatter = "snake_case"
+    user.code_private_variable_formatter = "snake_case"
+    user.code_public_variable_formatter = "snake_case"
+
+# Elixir-specific grammars
+state def: "def "
+state defp: "defp "
+state if: "if "
+state else: "else"
+state case: "case "
+state cond: "cond do"
+state try: "try do"
+state rescue: "rescue"
+state after: "after"
+state end: "end"
+
+op pipe: " |> "
+
+# Elixir-specific keywords and symbols
+[state] raise {user.elixir_exception}: user.insert_between("raise ", "")
+
+[state] rescue {user.elixir_exception}: "rescue {elixir_exception}"