Add erlang.application_start_argument configuration

Author: lpil

CHANGELOG.md

@@ -226,6 +226,12 @@
 
   ([sobolevn](https://github.com/sobolevn))
 
+- The `erlang.application_start_argument` parameter has been added to
+  `gleam.toml`. This is a string containing an Erlang term that will be written
+  into the package's Erlang `.app` file if `erlang.application_start_module`
+  has been set, replacing the default argument of `[]`.
+  ([Louis Pilfold](https://github.com/lpil))
+
 - Generated code for the JavaScript target now includes a public API which can
   be used for FFI interacting with Gleam custom types. For example, if you have
   this Gleam code:

compiler-cli/src/dependencies/tests.rs

@@ -1180,6 +1180,7 @@ fn package_config(
         links: vec![],
         erlang: ErlangConfig {
             application_start_module: None,
+            application_start_argument: None,
             extra_applications: vec![],
         },
         javascript: JavaScriptConfig {

compiler-core/src/codegen.rs

@@ -104,12 +104,17 @@ impl<'a> ErlangApp<'a> {
 
         let path = self.output_directory.join(format!("{}.app", &config.name));
 
-        let start_module = config
-            .erlang
-            .application_start_module
-            .as_ref()
-            .map(|module| tuple("mod", &format!("{{'{}', []}}", module_erlang_name(module))))
-            .unwrap_or_default();
+        let start_module = match config.erlang.application_start_module.as_ref() {
+            None => "".into(),
+            Some(module) => {
+                let module = module_erlang_name(module);
+                let argument = match config.erlang.application_start_argument.as_ref() {
+                    Some(argument) => argument.as_str(),
+                    None => "[]",
+                };
+                tuple("mod", &format!("{{'{module}', {argument}}}"))
+            }
+        };
 
         let modules = modules
             .iter()

compiler-core/src/config.rs

@@ -708,8 +708,16 @@ impl Default for PackageConfig {
 
 #[derive(Deserialize, Serialize, Debug, PartialEq, Eq, Default, Clone)]
 pub struct ErlangConfig {
+    /// An module that can be set in the `.app` file as the entrypoint for a stateful application
+    /// that defines a singleton supervision tree.
+    /// Erlang syntax.
     #[serde(default)]
     pub application_start_module: Option<EcoString>,
+    /// The argument for the start module start function. If not set then `[]` is used as the
+    /// default argument.
+    /// Erlang syntax.
+    #[serde(default)]
+    pub application_start_argument: Option<EcoString>,
     #[serde(default)]
     pub extra_applications: Vec<EcoString>,
 }

compiler-core/src/snapshots/gleam_core__config__barebones_package_config_to_json.snap

@@ -1,6 +1,6 @@
 ---
 source: compiler-core/src/config.rs
-assertion_line: 1116
+assertion_line: 1187
 expression: output
 snapshot_kind: text
 ---
@@ -27,6 +27,7 @@ version = "1.0.0"
   "links": [],
   "erlang": {
     "application_start_module": null,
+    "application_start_argument": null,
     "extra_applications": []
   },
   "javascript": {

compiler-core/src/snapshots/gleam_core__config__package_config_to_json.snap

@@ -1,6 +1,6 @@
 ---
 source: compiler-core/src/config.rs
-assertion_line: 1106
+assertion_line: 1171
 expression: output
 snapshot_kind: text
 ---
@@ -90,6 +90,7 @@ allow_read = ["./database.sqlite"]
   ],
   "erlang": {
     "application_start_module": "my_app/application",
+    "application_start_argument": null,
     "extra_applications": [
       "inets",
       "ssl"

compiler-core/src/snapshots/gleam_core__docs__barebones_package_config_to_json.snap

@@ -28,6 +28,7 @@ version = "1.0.0"
     "links": [],
     "erlang": {
       "application_start_module": null,
+      "application_start_argument": null,
       "extra_applications": []
     },
     "javascript": {

compiler-core/src/snapshots/gleam_core__docs__package_config_to_json.snap

@@ -1,6 +1,6 @@
 ---
 source: compiler-core/src/docs.rs
-assertion_line: 765
+assertion_line: 769
 expression: output
 snapshot_kind: text
 ---
@@ -91,6 +91,7 @@ allow_read = ["./database.sqlite"]
     ],
     "erlang": {
       "application_start_module": "my_app/application",
+      "application_start_argument": null,
       "extra_applications": [
         "inets",
         "ssl"

test-package-compiler/cases/erlang_app_generation_with_argument/gleam.toml

@@ -0,0 +1,22 @@
+# This config file has a bunch of properties that will be entered into the
+# Erlang .app file
+
+name = "my_erlang_application" # <-
+version = "0.1.0"              # <-
+description = "It's very cool" # <-
+
+target = "erlang"
+
+[erlang]
+extra_applications = ["inets", "ssl"] # <-
+application_start_module = "my_erlang_application_sup" # <-
+application_start_argument = "[1, two]" # <-
+
+[dependencies] # <-
+gleam_stdlib = "~> 1337.0"
+gleam_otp = "~> 1337.0"
+
+[dev-dependencies] # <-
+midas = "~> 1337.0"
+simple_json = "~> 1337.0"
+

test-package-compiler/cases/erlang_app_generation_with_argument/src/main.gleam

@@ -0,0 +1 @@
+