Make the unmonad script turn the let% into switch instead (#89)

* Make the unmonad script turn the let% into `switch` instead

Follow-up of #87

Now we can properly add error handling to these `None`/`Error(_)` later

* Check in the tests on 2 files

Supercedes #86

Author: chenglou

src/ppx2/Ppx_Unmonads.re

@@ -115,21 +115,31 @@ let mapper =
       | Pexp_extension(({txt: (
         "opt" | "opt_consume"
         | "try" | "try_wrap"
-        ) as txt, loc}, PStr([{pstr_desc: Pstr_eval({pexp_desc: Pexp_let(Nonrecursive, bindings, continuation)}, _attributes)}]))) => {
-        let (front, explanation) = switch (txt) {
-          | "opt" => ([%expr Monads.Option.bind], opt_explanation)
-          | "opt_consume" => ([%expr Monads.Option.consume], opt_consume_explanation)
-          | "try" => ([%expr Monads.Result.bind], "Sugar for the Result type")
-          | "try_wrap" => ([%expr Monads.Result.map], "Sugar for the Result type - auto-wraps in `Ok()`")
-          | _ => assert(false)
-        };
+        ) as txt}, PStr([{pstr_desc: Pstr_eval({pexp_desc: Pexp_let(Nonrecursive, bindings, continuation)}, _attributes)}]))) => {
         let (pat, expr) = process_bindings(bindings);
-        Ast_helper.Exp.attr(
-          [%expr [%e front]([%e mapper.expr(mapper, expr)], ~f=([%p pat]) => [%e mapper.expr(mapper, continuation)])],
-          ({txt: "ocaml.explanation", loc}, PStr([
-            Ast_helper.Str.eval(Ast_helper.Exp.constant(Pconst_string(explanation, None)))
-          ]))
-        )
+        switch (txt) {
+        | "opt" =>
+          [%expr [%e [%expr switch [%e mapper.expr(mapper, expr)] {
+          | None => None
+          | Some([%p pat]) => [%e mapper.expr(mapper, continuation)]
+          }]]]
+        | "opt_consume" =>
+          [%expr [%e [%expr switch [%e mapper.expr(mapper, expr)] {
+          | None => ()
+          | Some([%p pat]) => [%e mapper.expr(mapper, continuation)]
+          }]]]
+        | "try" =>
+          [%expr [%e [%expr switch [%e mapper.expr(mapper, expr)] {
+          | Error(e) => Error(e)
+          | Ok([%p pat]) => [%e mapper.expr(mapper, continuation)]
+          }]]]
+        | "try_wrap" =>
+          [%expr [%e [%expr switch [%e mapper.expr(mapper, expr)] {
+          | Error(e) => Error(e)
+          | Ok([%p pat]) => Ok([%e mapper.expr(mapper, continuation)])
+          }]]]
+        | _ => assert(false)
+        };
       }
       | _ => Ast_mapper.default_mapper.expr(mapper, expr)
       }

src/rescript-editor-support/BuildSystem.re

@@ -30,7 +30,8 @@ let getBsPlatformDir = rootPath => {
 let getCompiledBase = root => {
   Files.ifExists(root /+ "lib" /+ "bs");
 };
-let getStdlib = base => {
-  let%try_wrap bsPlatformDir = getBsPlatformDir(base);
-  bsPlatformDir /+ "lib" /+ "ocaml";
-};
+let getStdlib = base =>
+  switch (getBsPlatformDir(base)) {
+  | Error(e) => Error(e)
+  | Ok(bsPlatformDir) => Ok(bsPlatformDir /+ "lib" /+ "ocaml")
+  };

src/rescript-editor-support/FindFiles.re

@@ -299,36 +299,39 @@ let findDependencyFiles = (~debug, base, config) => {
                  let namespace = getNamespace(inner);
                  let directories =
                    getSourceDirectories(~includeDev=false, loc, inner);
-                 let%opt compiledBase = BuildSystem.getCompiledBase(loc);
                  /* |! "No compiled base found"; */
-                 if (debug) {
-                   Log.log("Compiled base: " ++ compiledBase);
+                 switch (BuildSystem.getCompiledBase(loc)) {
+                 | None => None
+                 | Some(compiledBase) =>
+                   if (debug) {
+                     Log.log("Compiled base: " ++ compiledBase);
+                   };
+                   let compiledDirectories =
+                     directories |> List.map(Files.fileConcat(compiledBase));
+                   let compiledDirectories =
+                     namespace == None
+                       ? compiledDirectories
+                       : [compiledBase, ...compiledDirectories];
+                   let files =
+                     findProjectFiles(
+                       ~debug,
+                       namespace,
+                       loc,
+                       directories,
+                       compiledBase,
+                     );
+                   /* let files =
+                      switch (namespace) {
+                      | None =>
+                         files
+                      | Some(namespace) =>
+                        files
+                        |> List.map(((name, paths)) =>
+                             (namespace ++ "-" ++ name, paths)
+                           )
+                      }; */
+                   Some((compiledDirectories, files));
                  };
-                 let compiledDirectories =
-                   directories |> List.map(Files.fileConcat(compiledBase));
-                 let compiledDirectories =
-                   namespace == None
-                     ? compiledDirectories
-                     : [compiledBase, ...compiledDirectories];
-                 let files =
-                   findProjectFiles(
-                     ~debug,
-                     namespace,
-                     loc,
-                     directories,
-                     compiledBase,
-                   );
-                 /* let files =
-                    switch (namespace) {
-                    | None =>
-                       files
-                    | Some(namespace) =>
-                      files
-                      |> List.map(((name, paths)) =>
-                           (namespace ++ "-" ++ name, paths)
-                         )
-                    }; */
-                 Some((compiledDirectories, files));
                | None => None
                };
              }
@@ -343,8 +346,11 @@ let findDependencyFiles = (~debug, base, config) => {
        });
   let (directories, files) = List.split(depFiles);
   let files = List.concat(files);
-  let%try stdlibDirectory = BuildSystem.getStdlib(base);
-  let directories = [stdlibDirectory, ...List.concat(directories)];
-  let results = files @ collectFiles(stdlibDirectory);
-  Ok((directories, results));
+  switch (BuildSystem.getStdlib(base)) {
+  | Error(e) => Error(e)
+  | Ok(stdlibDirectory) =>
+    let directories = [stdlibDirectory, ...List.concat(directories)];
+    let results = files @ collectFiles(stdlibDirectory);
+    Ok((directories, results));
+  };
 };