Add WASM support for Eliom apps

balat · balat · commit aa8ad9a5fc08 · 2026-01-30T16:03:16.000+01:00
diff --git a/dune-project b/dune-project
@@ -28,6 +28,7 @@ The client-side code is compiled to JS using Ocsigen Js_of_ocaml or to Wasm usin
   ppx_deriving
   (ppxlib (>= 0.15))
   (js_of_ocaml-compiler (>= 6.0))
+  wasm_of_ocaml-compiler
   (js_of_ocaml (>= 6.0))
   (js_of_ocaml-lwt (>= 6.0))
   (js_of_ocaml-ocamlbuild :build)
diff --git a/eliom.opam b/eliom.opam
@@ -23,6 +23,7 @@ depends: [
   "ppx_deriving"
   "ppxlib" {>= "0.15"}
   "js_of_ocaml-compiler" {>= "6.0"}
+  "wasm_of_ocaml-compiler"
   "js_of_ocaml" {>= "6.0"}
   "js_of_ocaml-lwt" {>= "6.0"}
   "js_of_ocaml-ocamlbuild" {build}
diff --git a/pkg/distillery/templates/app.exe/Makefile.app b/pkg/distillery/templates/app.exe/Makefile.app
@@ -67,6 +67,15 @@ install.static: $(TEST_PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).js | $(PREFIX)$(
 	HASH=`md5sum _build/default/client/$(PROJECT_NAME).bc.js | cut -d ' ' -f 1` && \
 	install $(addprefix -o ,$(WWWUSER)) $(JS_PREFIX)_$$HASH.js $(PREFIX)$(ELIOMSTATICDIR) && \
 	ln -sf $(PROJECT_NAME)_$$HASH.js $(PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).js
+ifeq ($(ENABLE_WASM),yes)
+	HASH_WASM=`md5sum _build/default/client/$(PROJECT_NAME).bc.wasm.js | cut -d ' ' -f 1` && \
+	install $(addprefix -o ,$(WWWUSER)) $(JS_PREFIX)_$$HASH_WASM.wasm.js $(PREFIX)$(ELIOMSTATICDIR) && \
+	ln -sf $(PROJECT_NAME)_$$HASH_WASM.wasm.js $(PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).wasm.js
+	if [ -d _build/default/client/$(PROJECT_NAME).bc.wasm.assets ]; then \
+	  cp -rf _build/default/client/$(PROJECT_NAME).bc.wasm.assets $(PREFIX)$(ELIOMSTATICDIR)/; \
+	  [ -z $(WWWUSER) ] || chown -R $(WWWUSER) $(PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).bc.wasm.assets; \
+	fi
+endif
 	[ -z $(WWWUSER) ] || chown -R $(WWWUSER) $(PREFIX)$(FILESDIR)
 
 .PHONY:
@@ -91,13 +100,24 @@ config-files: | $(TEST_PREFIX)$(ELIOMSTATICDIR) $(TEST_PREFIX)$(LIBDIR)
 	HASH=`md5sum _build/default/client/$(PROJECT_NAME).bc.js | cut -d ' ' -f 1` && \
 	cp -f _build/default/client/$(PROJECT_NAME).bc.js $(JS_PREFIX)_$$HASH.js && \
 	ln -sf $(PROJECT_NAME)_$$HASH.js $(JS_PREFIX).js
+ifeq ($(ENABLE_WASM),yes)
+	HASH_WASM=`md5sum _build/default/client/$(PROJECT_NAME).bc.wasm.js | cut -d ' ' -f 1` && \
+	cp -f _build/default/client/$(PROJECT_NAME).bc.wasm.js $(JS_PREFIX)_$$HASH_WASM.wasm.js && \
+	ln -sf $(PROJECT_NAME)_$$HASH_WASM.wasm.js $(JS_PREFIX).wasm.js
+	if [ -d _build/default/client/$(PROJECT_NAME).bc.wasm.assets ]; then \
+	  cp -rf _build/default/client/$(PROJECT_NAME).bc.wasm.assets $(TEST_PREFIX)$(ELIOMSTATICDIR)/; \
+	fi
+endif
 	cp -f _build/default/$(PROJECT_NAME).cm* $(TEST_PREFIX)$(LIBDIR)/
 
 all::
 	$(ENV_PSQL) dune build $(DUNE_OPTIONS) @install @$(PROJECT_NAME)
 
 js::
 	$(ENV_PSQL) dune build $(DUNE_OPTIONS) client/$(PROJECT_NAME).bc.js
+ifeq ($(ENABLE_WASM),yes)
+	$(ENV_PSQL) dune build $(DUNE_OPTIONS) client/$(PROJECT_NAME).bc.wasm.js
+endif
 
 byte:: js
 	$(ENV_PSQL) dune build $(DUNE_OPTIONS) $(PROJECT_NAME)_main.bc
diff --git a/pkg/distillery/templates/app.exe/Makefile.options b/pkg/distillery/templates/app.exe/Makefile.options
@@ -73,5 +73,8 @@ CSS_PREFIX            := $(LOCAL_STATIC_CSS)/${PROJECT_NAME}
 # JavaScript, ocsigenserver
 DEBUG                 := yes
 
+# Enable WASM compilation (yes/no): Requires wasm_of_ocaml (enabled by default)
+ENABLE_WASM           := yes
+
 ##----------------------------------------------------------------------
 
diff --git a/pkg/distillery/templates/app.exe/PROJECT_NAME.eliom b/pkg/distillery/templates/app.exe/PROJECT_NAME.eliom
@@ -5,7 +5,10 @@ let%server application_name = "%%%PROJECT_NAME%%%"
 let%client application_name = Eliom_client.get_application_name ()
 
 let%server () =
-    Ocsipersist_settings.set_db_file "local/var/data/%%%PROJECT_NAME%%%/%%%PROJECT_NAME%%%_db";
+    Ocsipersist_settings.set_db_file "local/var/data/%%%PROJECT_NAME%%%/%%%PROJECT_NAME%%%_db"
+    (* WebAssembly support with automatic browser detection is enabled by default.
+       To disable it, uncomment the following line: *)
+    (* ; Eliom_config.set_enable_wasm false *)
 
 (* Create a module for the application. See
    https://ocsigen.org/eliom/manual/clientserver-applications for more
diff --git a/pkg/distillery/templates/app.exe/dune b/pkg/distillery/templates/app.exe/dune
@@ -86,7 +86,7 @@
  client
  (executables
   (names %%%PROJECT_NAME%%%)
-  (modes js byte)
+  (modes js byte wasm)
   (preprocess
    (pps
     js_of_ocaml-ppx
@@ -109,6 +109,8 @@
     use-js-string
     --no-source-map))
   ; source maps are slow...
+  (wasm_of_ocaml
+   (flags :standard))
   (libraries eliom.client))
  (dynamic_include ../gen/dune.client))
 
@@ -122,6 +124,7 @@
   %%%PROJECT_NAME%%%_main.exe
   client/%%%PROJECT_NAME%%%.bc
   client/%%%PROJECT_NAME%%%.bc.js
+  client/%%%PROJECT_NAME%%%.bc.wasm.js
   tools/check_modules.ml)
  (action
   (run ocaml -I +unix -I +str tools/check_modules.ml %%%PROJECT_NAME%%%)))
diff --git a/pkg/distillery/templates/app.exe/dune-project b/pkg/distillery/templates/app.exe/dune-project
@@ -1,10 +1,13 @@
-(lang dune 3.14)
+(lang dune 3.17)
 
 (dialect
  (name "eliom-server")
- (implementation (extension "eliom"))
- (interface (extension "eliomi")))
+ (implementation
+  (extension "eliom"))
+ (interface
+  (extension "eliomi")))
 
 (wrapped_executables false)
 
-(formatting (enabled_for ocaml "eliom-server"))
+(formatting
+ (enabled_for ocaml "eliom-server"))
diff --git a/pkg/distillery/templates/app.lib/Makefile.app b/pkg/distillery/templates/app.lib/Makefile.app
@@ -74,6 +74,15 @@ install.static: $(TEST_PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).js | $(PREFIX)$(
 	HASH=`md5sum _build/default/client/$(PROJECT_NAME).bc.js | cut -d ' ' -f 1` && \
 	install $(addprefix -o ,$(WWWUSER)) $(JS_PREFIX)_$$HASH.js $(PREFIX)$(ELIOMSTATICDIR) && \
 	ln -sf $(PROJECT_NAME)_$$HASH.js $(PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).js
+ifeq ($(ENABLE_WASM),yes)
+	HASH_WASM=`md5sum _build/default/client/$(PROJECT_NAME).bc.wasm.js | cut -d ' ' -f 1` && \
+	install $(addprefix -o ,$(WWWUSER)) $(JS_PREFIX)_$$HASH_WASM.wasm.js $(PREFIX)$(ELIOMSTATICDIR) && \
+	ln -sf $(PROJECT_NAME)_$$HASH_WASM.wasm.js $(PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).wasm.js
+	if [ -d _build/default/client/$(PROJECT_NAME).bc.wasm.assets ]; then \
+	  cp -rf _build/default/client/$(PROJECT_NAME).bc.wasm.assets $(PREFIX)$(ELIOMSTATICDIR)/; \
+	  [ -z $(WWWUSER) ] || chown -R $(WWWUSER) $(PREFIX)$(ELIOMSTATICDIR)/$(PROJECT_NAME).bc.wasm.assets; \
+	fi
+endif
 	[ -z $(WWWUSER) ] || chown -R $(WWWUSER) $(PREFIX)$(FILESDIR)
 install.etc: $(TEST_PREFIX)$(ETCDIR)/$(PROJECT_NAME).conf | $(PREFIX)$(ETCDIR)
 	install $< $(PREFIX)$(ETCDIR)/$(PROJECT_NAME).conf
@@ -122,6 +131,11 @@ SED_ARGS += -e "s|%%FILESDIR%%|%%PREFIX%%$(FILESDIR)|g"
 SED_ARGS += -e "s|%%ELIOMSTATICDIR%%|%%PREFIX%%$(ELIOMSTATICDIR)|g"
 SED_ARGS += -e "s|%%APPNAME%%|$(shell basename `readlink $(JS_PREFIX).js` .js)|g"
 SED_ARGS += -e "s|%%CSSNAME%%|$(shell readlink $(CSS_PREFIX).css)|g"
+ifeq ($(ENABLE_WASM),yes)
+  SED_ARGS += -e "s|%%WASMATTR%%|wasm=\"$(shell basename `readlink $(JS_PREFIX).wasm.js` .wasm.js).wasm.js\"|g"
+else
+  SED_ARGS += -e "s|%%WASMATTR%%||g"
+endif
 ifeq ($(DEBUG),yes)
   SED_ARGS += -e "s|%%DEBUGMODE%%|\<debugmode /\>|g"
 else
@@ -156,6 +170,14 @@ config-files: | $(TEST_PREFIX)$(ELIOMSTATICDIR) $(TEST_PREFIX)$(LIBDIR)
 	HASH=`md5sum _build/default/client/$(PROJECT_NAME).bc.js | cut -d ' ' -f 1` && \
 	cp -f _build/default/client/$(PROJECT_NAME).bc.js $(JS_PREFIX)_$$HASH.js && \
 	ln -sf $(PROJECT_NAME)_$$HASH.js $(JS_PREFIX).js
+ifeq ($(ENABLE_WASM),yes)
+	HASH_WASM=`md5sum _build/default/client/$(PROJECT_NAME).bc.wasm.js | cut -d ' ' -f 1` && \
+	cp -f _build/default/client/$(PROJECT_NAME).bc.wasm.js $(JS_PREFIX)_$$HASH_WASM.wasm.js && \
+	ln -sf $(PROJECT_NAME)_$$HASH_WASM.wasm.js $(JS_PREFIX).wasm.js
+	if [ -d _build/default/client/$(PROJECT_NAME).bc.wasm.assets ]; then \
+	  cp -rf _build/default/client/$(PROJECT_NAME).bc.wasm.assets $(TEST_PREFIX)$(ELIOMSTATICDIR)/; \
+	fi
+endif
 	cp -f _build/default/$(PROJECT_NAME).cm* $(TEST_PREFIX)$(LIBDIR)/
 	$(MAKE) $(CONFIG_FILES) $(TEST_CONFIG_FILES) PROJECT_NAME=$(PROJECT_NAME)
 
@@ -164,6 +186,9 @@ all::
 
 js::
 	$(ENV_PSQL) dune build $(DUNE_OPTIONS) client/$(PROJECT_NAME).bc.js
+ifeq ($(ENABLE_WASM),yes)
+	$(ENV_PSQL) dune build $(DUNE_OPTIONS) client/$(PROJECT_NAME).bc.wasm.js
+endif
 
 byte::
 	$(ENV_PSQL) dune build $(DUNE_OPTIONS) @$(PROJECT_NAME)
diff --git a/pkg/distillery/templates/app.lib/Makefile.options b/pkg/distillery/templates/app.lib/Makefile.options
@@ -73,5 +73,8 @@ CSS_PREFIX            := $(LOCAL_STATIC_CSS)/${PROJECT_NAME}
 # JavaScript, ocsigenserver
 DEBUG                 := yes
 
+# Enable WASM compilation (yes/no): Requires wasm_of_ocaml (enabled by default)
+ENABLE_WASM           := yes
+
 ##----------------------------------------------------------------------
 
diff --git a/pkg/distillery/templates/app.lib/PROJECT_NAME.conf.in b/pkg/distillery/templates/app.lib/PROJECT_NAME.conf.in
@@ -41,6 +41,8 @@
     <extension findlib-package="eliom.server">
       <!-- Ask Eliom to ignore UTM parameters and others: -->
       <ignoredgetparams regexp="utm_[a-z]*|[a-z]*clid|li_fat_id"/>
+      <!-- Enable WebAssembly support with automatic browser detection: -->
+      <wasm enabled="true"/>
 <!-- Uncomment if you are using https only and want secure cookies:
        <securecookies value="true" />
   -->
@@ -51,7 +53,7 @@
       <static dir="%%FILESDIR%%" />
       %%ELIOM_MODULES%%
       <eliommodule module="%%LIBDIR%%/%%PROJECT_NAME%%.cma">
-        <app name="%%APPNAME%%" css="%%CSSNAME%%" />
+        <app name="%%APPNAME%%" css="%%CSSNAME%%" %%WASMATTR%% />
         <avatars dir="%%FILESDIR%%/avatars" />
         <os-db
           host="%%DB_HOST%%"
diff --git a/pkg/distillery/templates/app.lib/dune b/pkg/distillery/templates/app.lib/dune
@@ -57,7 +57,7 @@
  client
  (executables
   (names %%%PROJECT_NAME%%%)
-  (modes js byte)
+  (modes js byte wasm)
   (preprocess
    (pps
     js_of_ocaml-ppx
@@ -80,6 +80,8 @@
     use-js-string
     --no-source-map))
   ; source maps are slow...
+  (wasm_of_ocaml
+   (flags :standard))
   (libraries eliom.client))
  (dynamic_include ../gen/dune.client))
 
@@ -91,6 +93,7 @@
   %%%PROJECT_NAME%%%.cma
   client/%%%PROJECT_NAME%%%.bc
   client/%%%PROJECT_NAME%%%.bc.js
+  client/%%%PROJECT_NAME%%%.bc.wasm.js
   tools/check_modules.ml)
  (action
   (run ocaml -I +unix -I +str tools/check_modules.ml %%%PROJECT_NAME%%%)))
diff --git a/pkg/distillery/templates/app.lib/dune-project b/pkg/distillery/templates/app.lib/dune-project
@@ -1,10 +1,13 @@
-(lang dune 3.14)
+(lang dune 3.17)
 
 (dialect
  (name "eliom-server")
- (implementation (extension "eliom"))
- (interface (extension "eliomi")))
+ (implementation
+  (extension "eliom"))
+ (interface
+  (extension "eliomi")))
 
 (wrapped_executables false)
 
-(formatting (enabled_for ocaml "eliom-server"))
+(formatting
+ (enabled_for ocaml "eliom-server"))
diff --git a/pkg/distillery/templates/basic.ppx/Makefile b/pkg/distillery/templates/basic.ppx/Makefile
@@ -1,4 +1,7 @@
 
+# NOTE: WASM support is only available in modern templates (app.exe, app.lib)
+# This legacy template (basic.ppx) does not support wasm_of_ocaml compilation
+#
 ##----------------------------------------------------------------------
 ## DISCLAIMER
 ##
diff --git a/src/lib/client/dune b/src/lib/client/dune
@@ -33,7 +33,9 @@
   (language c)
   (names eliom_stubs))
  (js_of_ocaml
-  (javascript_files eliom_client.js)))
+  (javascript_files eliom_client.js))
+ (wasm_of_ocaml
+  (wasm_files eliom_client.wat)))
 
 (include dune.client)
 
diff --git a/src/lib/eliom.server.ml b/src/lib/eliom.server.ml
@@ -16,6 +16,7 @@ let run
       ?max_anonymous_services_per_session
       ?secure_cookies
       ?application_script
+      ?enable_wasm
       ?global_data_caching
       ?html_content_type
       ?ignored_get_params
@@ -74,6 +75,9 @@ let run
     max_anonymous_services_per_session;
   Option.iter (fun v -> sitedata.secure_cookies <- v) secure_cookies;
   Option.iter (fun v -> sitedata.application_script <- v) application_script;
+  (* Always update enable_wasm: use provided value or current global default *)
+  sitedata.enable_wasm <-
+    Option.value enable_wasm ~default:!Eliommod.default_enable_wasm;
   Option.iter (fun v -> sitedata.cache_global_data <- v) global_data_caching;
   Option.iter (fun v -> sitedata.html_content_type <- Some v) html_content_type;
   Option.iter
diff --git a/src/lib/eliom.server.mli b/src/lib/eliom.server.mli
@@ -32,6 +32,7 @@ val run :
   -> ?max_anonymous_services_per_session:int * bool
   -> ?secure_cookies:bool
   -> ?application_script:bool * bool
+  -> ?enable_wasm:bool
   -> ?global_data_caching:(string list * int) option
   -> ?html_content_type:string
   -> ?ignored_get_params:string * Re.re
@@ -42,4 +43,9 @@ val run :
 (** [run ?app ()] run Eliom application [app] under current site.
     Use this to build a static executable without configuration file.
     Default value of [?app] is [default_app_name].
-    Other optional values correspond to Eliom configuration for this site. *)
+    Other optional values correspond to Eliom configuration for this site.
+
+    WebAssembly support is enabled by default (?enable_wasm defaults to true). When enabled,
+    the server will generate a detection script that loads the WASM version
+    of your client code if the browser supports WebAssembly, with automatic
+    fallback to JavaScript for browsers that don't support it. *)
diff --git a/src/lib/eliom_common.server.ml b/src/lib/eliom_common.server.ml
@@ -493,7 +493,8 @@ and sitedata =
   ; mutable ipv6mask : int option * bool
   ; mutable application_script : bool (* defer *) * bool
   ; (* async *)
-    mutable cache_global_data : (string list * int) option
+    mutable enable_wasm : bool
+  ; mutable cache_global_data : (string list * int) option
   ; mutable html_content_type : string option
   ; mutable ignored_get_params : (string * Re.re) list
   ; mutable ignored_post_params : (string * Re.re) list
diff --git a/src/lib/eliom_common.server.mli b/src/lib/eliom_common.server.mli
@@ -558,7 +558,8 @@ and sitedata =
   ; mutable ipv6mask : int option * bool
   ; mutable application_script : bool (* defer *) * bool
   ; (* async *)
-    mutable cache_global_data : (string list * int) option
+    mutable enable_wasm : bool
+  ; mutable cache_global_data : (string list * int) option
   ; mutable html_content_type : string option
   ; mutable ignored_get_params : (string * Re.re) list
   ; mutable ignored_post_params : (string * Re.re) list
diff --git a/src/lib/eliom_config.server.ml b/src/lib/eliom_config.server.ml
@@ -76,6 +76,8 @@ let set_max_volatile_groups_per_site v =
 
 let set_secure_cookies v = Eliommod.default_secure_cookies := v
 let set_application_script v = Eliommod.default_application_script := v
+let set_enable_wasm v = Eliommod.default_enable_wasm := v
+let get_enable_wasm () = !Eliommod.default_enable_wasm
 let set_cache_global_data v = Eliommod.default_cache_global_data := v
 let set_html_content_type v = Eliommod.default_html_content_type := Some v
 
diff --git a/src/lib/eliom_config.server.mli b/src/lib/eliom_config.server.mli
@@ -86,6 +86,20 @@ val set_max_anonymous_services_per_session : int -> unit
 val set_max_volatile_groups_per_site : int -> unit
 val set_secure_cookies : bool -> unit
 val set_application_script : bool * bool -> unit
+
+val set_enable_wasm : bool -> unit
+(** Enable or disable WebAssembly support with automatic browser detection.
+    When enabled (default), Eliom will generate a script that detects WebAssembly
+    support in the browser and loads either the WASM version (.wasm.js) or
+    the JavaScript fallback (.js) accordingly.
+
+    This setting can be overridden per-site using the [~enable_wasm] parameter
+    of {!Eliom.run} or the [<wasm enabled="true|false"/>] tag in the
+    configuration file. *)
+
+val get_enable_wasm : unit -> bool
+(** Get the current global setting for WebAssembly support. *)
+
 val set_cache_global_data : (Eliom_lib.Url.path * int) option -> unit
 val set_html_content_type : string -> unit
 val add_ignored_get_params : string * Re.re -> unit
diff --git a/src/lib/eliom_registration.server.ml b/src/lib/eliom_registration.server.ml
diff --git a/src/lib/eliom_registration.server.mli b/src/lib/eliom_registration.server.mli
diff --git a/src/lib/server/eliommod.ml b/src/lib/server/eliommod.ml
diff --git a/src/lib/server/eliommod.mli b/src/lib/server/eliommod.mli
