feat: add gleam (#206)

README.md

@@ -245,6 +245,7 @@ functions.
 * fourmolu
 * fprettify
 * gdformat
+* gleam
 * gofmt
 * gofumpt
 * google-java-format

examples/formatter-gleam.toml

@@ -0,0 +1,6 @@
+# Example generated by ../examples.sh
+[formatter.gleam]
+command = "gleam"
+excludes = []
+includes = ["*.gleam"]
+options = ["format"]

programs/gleam.nix

@@ -0,0 +1,20 @@
+{ lib, pkgs, config, ... }:
+let
+  cfg = config.programs.gleam;
+in
+{
+  meta.maintainers = [ "anntnzrb" ];
+
+  options.programs.gleam = {
+    enable = lib.mkEnableOption "gleam";
+    package = lib.mkPackageOption pkgs "gleam" { };
+  };
+
+  config = lib.mkIf cfg.enable {
+    settings.formatter.gleam = {
+      command = cfg.package;
+      options = [ "format" ];
+      includes = [ "*.gleam" ];
+    };
+  };
+}