Add a 'modules' plugin with helpers to compile modules

This will be done by Clerk at some point, but the plugin is useful for the time being.

compiler/driver.ml

@@ -684,7 +684,7 @@ module Commands = struct
       | FileName n -> Some (modname_of_file n)
       | _ -> None
     in
-    Lcalc.To_ocaml.format_program fmt ?modname prg type_ordering
+    Lcalc.To_ocaml.format_program fmt ?register_module:modname prg type_ordering
 
   let ocaml_cmd =
     Cmd.v

compiler/lcalc/to_ocaml.ml

@@ -545,6 +545,32 @@ let format_code_items
         String.Map.add (Mark.remove (ScopeName.get_info name)) var bnd)
     ~init:String.Map.empty code_items
 
+let format_scope_exec
+    (ctx : decl_ctx)
+    (fmt : Format.formatter)
+    (bnd : 'm Ast.expr Var.t String.Map.t)
+    scope_name
+    scope_body =
+  let scope_name_str = Mark.remove (ScopeName.get_info scope_name) in
+  let scope_var = String.Map.find scope_name_str bnd in
+  let scope_input =
+    StructName.Map.find scope_body.scope_body_input_struct ctx.ctx_structs
+  in
+  if not (StructField.Map.is_empty scope_input) then
+    Message.raise_error
+      "The scope @{<bold>%s@} defines input variables.@ This is not supported \
+       for a main scope at the moment."
+      scope_name_str;
+  Format.pp_open_vbox fmt 2;
+  Format.pp_print_string fmt "let _ =";
+  (* TODO: dump the output using yojson that should be already available from
+     the runtime *)
+  Format.pp_print_space fmt ();
+  format_var fmt scope_var;
+  Format.pp_print_space fmt ();
+  Format.pp_print_string fmt "()";
+  Format.pp_close_box fmt ()
+
 let format_module_registration
     fmt
     (bnd : 'm Ast.expr Var.t String.Map.t)
@@ -584,11 +610,21 @@ open Runtime_ocaml.Runtime
 
 let format_program
     (fmt : Format.formatter)
-    ?modname
+    ?register_module
+    ?exec_scope
     (p : 'm Ast.program)
     (type_ordering : Scopelang.Dependency.TVertex.t list) : unit =
   Format.pp_print_string fmt header;
   format_ctx type_ordering fmt p.decl_ctx;
   let bnd = format_code_items p.decl_ctx fmt p.code_items in
   Format.pp_print_newline fmt ();
-  Option.iter (format_module_registration fmt bnd) modname
+  match register_module, exec_scope with
+  | Some modname, None -> format_module_registration fmt bnd modname
+  | None, Some scope_name ->
+    let scope_body = Program.get_scope_body p scope_name in
+    format_scope_exec p.decl_ctx fmt bnd scope_name scope_body
+  | None, None -> ()
+  | Some _, Some _ ->
+    Message.raise_error
+      "OCaml generation: both module registration and top-level scope \
+       execution where required at the same time."

compiler/lcalc/to_ocaml.mli

@@ -40,9 +40,15 @@ val format_var : Format.formatter -> 'm Var.t -> unit
 
 val format_program :
   Format.formatter ->
-  ?modname:string ->
+  ?register_module:string ->
+  ?exec_scope:ScopeName.t ->
   'm Ast.program ->
   Scopelang.Dependency.TVertex.t list ->
   unit
-(** Usage [format_program fmt p type_dependencies_ordering]. If [modname] is
-    set, registers the module for dynamic loading *)
+(** Usage [format_program fmt p type_dependencies_ordering]. Either one of these
+    may be set:
+
+    - [register_module] will register the module for dynamic loading under the
+      given name
+    - [exec_scope] will mark the named scope as "main" and execute it at the end
+      of the program. It must have no inputs. *)

compiler/plugins/api_web.ml

@@ -453,7 +453,7 @@ let run
     Message.emit_debug "Compiling program into OCaml...";
     Message.emit_debug "Writing to %s..."
       (Option.value ~default:"stdout" output_file);
-    Lcalc.To_ocaml.format_program fmt ?modname prg type_ordering
+    Lcalc.To_ocaml.format_program fmt ?register_module:modname prg type_ordering
   in
   let jsoo_output_file, with_formatter =
     Driver.Commands.get_output_format options ~ext:"_api_web.ml" output

compiler/plugins/dune

@@ -28,6 +28,13 @@
  (modules lazy_interp)
  (libraries shared_ast catala.driver))
 
+(library
+ (name modules)
+ (public_name catala.plugins.modules)
+ (synopsis "Catala plugin for experimental module handling tooling")
+ (modules modules)
+ (libraries shared_ast catala.driver))
+
 (documentation
  (package catala)
  (mld_files plugins))

compiler/plugins/modules.ml

@@ -0,0 +1,215 @@
+(* This file is part of the Catala compiler, a specification language for tax
+   and social benefits computation rules. Copyright (C) 2020 Inria, contributor:
+   Louis Gesbert <louis.gesbert@inria.fr>.
+
+   Licensed under the Apache License, Version 2.0 (the "License"); you may not
+   use this file except in compliance with the License. You may obtain a copy of
+   the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+   WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+   License for the specific language governing permissions and limitations under
+   the License. *)
+
+open Catala_utils
+
+let action_flag =
+  let docs = "ACTIONS" in
+  let open Cmdliner.Arg in
+  required
+  & vflag None
+      [
+        ( Some `Compile,
+          info ["compile"] ~docs
+            ~doc:
+              "Compiles a Catala file into a module: a $(b,.cmxs) file that \
+               can be used by the Catala interpreter."
+          (* "and $(b,cmo) and $(b,cmx) files that can be linked into an OCaml
+             program" *) );
+        ( Some `Link,
+          info ["link"] ~docs
+            ~doc:
+              "Compiles and links a catala program into a binary (using the \
+               ocaml backend). Specify a main scope using the $(b,--scope) \
+               flag to be run upon execution. This is still pretty useless at \
+               the moment besides for testing purposes, as there is no way to \
+               feed input to the generated program, and the output will be \
+               silent. Assertions will be checked, though." );
+      ]
+
+let gen_ocaml options link_modules optimize check_invariants modname main =
+  let prg, ctx, type_ordering =
+    Driver.Passes.lcalc options ~link_modules ~optimize ~check_invariants
+      ~avoid_exceptions:false ~closure_conversion:false
+  in
+  let exec_scope = Option.map (Driver.Commands.get_scope_uid ctx) main in
+  let filename, with_output =
+    Driver.Commands.get_output_format options ~ext:".ml" None
+  in
+  with_output
+  @@ fun ppf ->
+  Lcalc.To_ocaml.format_program ppf ?register_module:modname ?exec_scope prg
+    type_ordering;
+  Option.get filename
+
+let run_process cmd args =
+  Message.emit_debug "Running @[<hov 4>@{<yellow>@{<bold>%s@} %a@}@}@]" cmd
+    (Format.pp_print_list ~pp_sep:Format.pp_print_space Format.pp_print_string)
+    args;
+  match
+    Unix.waitpid []
+      (Unix.create_process cmd
+         (Array.of_list (cmd :: args))
+         Unix.stdin Unix.stdout Unix.stderr)
+  with
+  | _, Unix.WEXITED 0 -> ()
+  | _, _ -> Message.raise_error "Child process @{<bold>%s@} failed" cmd
+
+let with_flag flag args =
+  List.fold_right (fun p acc -> flag :: p :: acc) args []
+
+let ocaml_libdir =
+  lazy
+    (try String.trim (File.process_out "opam" ["var"; "lib"])
+     with Failure _ -> (
+       try String.trim (File.process_out "ocamlc" ["-where"])
+       with Failure _ -> (
+         match File.(check_directory (Sys.executable_name / ".." / "lib")) with
+         | Some d -> d
+         | None ->
+           Message.raise_error
+             "Could not locate the OCaml library directory, make sure OCaml or \
+              opam is installed")))
+
+let runtime_dir =
+  lazy
+    (match
+       List.find_map File.check_directory
+         [
+           "_build/install/default/lib/catala/runtime_ocaml";
+           (* Relative dir when running from catala source *)
+           File.(Lazy.force ocaml_libdir / "catala" / "runtime");
+         ]
+     with
+    | Some dir ->
+      Message.emit_debug "Catala runtime libraries found at @{<bold>%s@}." dir;
+      dir
+    | None ->
+      Message.raise_error
+        "Could not locate the Catala runtime library.@ Make sure that either \
+         catala is correctly installed,@ or you are running from the root of a \
+         compiled source tree.")
+
+let compile options link_modules optimize check_invariants =
+  let modname =
+    match options.Cli.input_file with
+    (* TODO: extract module name from directives *)
+    | FileName n -> Driver.modname_of_file n
+    | _ -> Message.raise_error "Input must be a file name for this command"
+  in
+  let basename = String.uncapitalize_ascii modname in
+  let ml_file =
+    gen_ocaml options link_modules optimize check_invariants (Some modname) None
+  in
+  let flags = ["-I"; Lazy.force runtime_dir] in
+  let shared_out = basename ^ ".cmxs" in
+  Message.emit_debug "Compiling OCaml shared object file @{<bold>%s@}..."
+    shared_out;
+  run_process "ocamlopt" ("-shared" :: ml_file :: "-o" :: shared_out :: flags);
+  (* let byte_out = basename ^ ".cmo" in
+   * Message.emit_debug "Compiling OCaml byte-code object file @{<bold>%s@}..." byte_out;
+   * run_process "ocamlc" ("-c" :: ml_file :: "-o" :: byte_out :: flags);
+   * let native_out = basename ^ ".cmx" in
+   * Message.emit_debug "Compiling OCaml native object file @{<bold>%s@}..." native_out;
+   * run_process "ocamlopt" ("-c" :: ml_file :: "-o" :: native_out ::flags); *)
+  Message.emit_debug "Done."
+
+let link options link_modules optimize check_invariants output ex_scope_opt =
+  let ml_file =
+    gen_ocaml options link_modules optimize check_invariants None ex_scope_opt
+  in
+  (* NOTE: assuming native target at the moment *)
+  let cmd = "ocamlopt" in
+  let ocaml_libdir = Lazy.force ocaml_libdir in
+  let runtime_dir = Lazy.force runtime_dir in
+  (* Recursive dependencies are expanded manually here. A shorter version would
+     use [ocamlfind ocalmopt -linkpkg -package] with just ppx_yojson_conv_lib,
+     zarith and dates_calc *)
+  let link_libs =
+    [
+      "biniou";
+      "easy-format";
+      "yojson";
+      "ppx_yojson_conv_lib";
+      "zarith";
+      "dates_calc";
+    ]
+  in
+  let link_libdirs =
+    List.map
+      (fun lib ->
+        match File.(check_directory (ocaml_libdir / lib)) with
+        | None ->
+          Message.raise_error
+            "Required OCaml library not found at @{<bold>%s@}.@ Try `opam \
+             install %s'"
+            File.(ocaml_libdir / lib)
+            lib
+        | Some l -> l)
+      link_libs
+  in
+  let runtime_lib = File.(runtime_dir / "runtime_ocaml.cmxa") in
+  let modules =
+    List.map (fun m -> Filename.remove_extension m ^ ".ml") link_modules
+  in
+  let output =
+    match output with
+    | Some o -> o
+    | None -> Filename.remove_extension ml_file ^ ".exe"
+  in
+  let args =
+    with_flag "-I" link_libdirs
+    @ List.map
+        (fun lib -> String.map (function '-' -> '_' | c -> c) lib ^ ".cmxa")
+        link_libs
+    @ ("-I" :: runtime_dir :: runtime_lib :: modules)
+    @ [ml_file; "-o"; output]
+  in
+  run_process cmd args;
+  Message.emit_result "Successfully generated @{<bold>%s@}" output
+(* Compile from ml and link the modules cmx. => ocamlfind ocamlopt -linkpkg
+   -package ppx_yojson_conv_lib -package zarith -package dates_calc -I
+   _build/default/runtimes/ocaml/.runtime_ocaml.objs/byte
+   _build/default/runtimes/ocaml/runtime_ocaml.cmxa ext.cmx extuse.ml *)
+
+let run
+    action
+    link_modules
+    optimize
+    check_invariants
+    output
+    ex_scope_opt
+    options =
+  match action with
+  | `Compile -> compile options link_modules optimize check_invariants
+  | `Link ->
+    link options link_modules optimize check_invariants ex_scope_opt output
+
+let term =
+  let open Cmdliner.Term in
+  const run
+  $ action_flag
+  $ Cli.Flags.link_modules
+  $ Cli.Flags.optimize
+  $ Cli.Flags.check_invariants
+  $ Cli.Flags.ex_scope_opt
+  $ Cli.Flags.output
+
+let () =
+  Driver.Plugin.register "module" term
+    ~doc:
+      "This plugin provides a few experimental tools related to module \
+       generation and compilation"