melange: define MELANGE conditional compilation variable (#472)

* melange: define `MELANGE` conditional compilation variable * add changelog entry
melange-re · Jan 16, 2023 · 0be7b28 · 0be7b28
1 parent 781978a
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Showing 4 changed files with 27 additions and 3 deletions.
diff --git a/Changes.md b/Changes.md
@@ -21,6 +21,8 @@ Unreleased
   [`NonEscapeCharacter`](https://tc39.es/ecma262/#prod-NonEscapeCharacter)
   correctly in JS strings (those written using `{js|string here|js}`)
   ([#469](https://github.com/melange-re/melange/pull/469))
+- [melange]: define `MELANGE` conditional compilation variable
+  ([#472](https://github.com/melange-re/melange/pull/472))
 
 0.3.2 2022-11-19
 ---------------

diff --git a/flake.lock b/flake.lock
diff --git a/jscomp/core/bs_conditional_initial.ml b/jscomp/core/bs_conditional_initial.ml
@@ -66,6 +66,7 @@ let setup_env () =
     Printexc.record_backtrace true;
 #endif
 
+  Rescript_cpp.replace_directive_bool "MELANGE" true;
   Rescript_cpp.replace_directive_bool "BS" true;
   Rescript_cpp.replace_directive_bool "JS" true;
   Rescript_cpp.replace_directive_string "BS_VERSION"  Melange_version.version

diff --git a/test/melange-conditional.t b/test/melange-conditional.t
@@ -0,0 +1,21 @@
+Demonstrate the `#if MELANGE` conditional variable
+
+  $ export MELANGELIB="$INSIDE_DUNE/lib/melange"
+  $ cat > x.ml <<EOF
+  > let () =
+  > #if MELANGE then
+  >   Js.log("It's Melange");
+  > #else
+  >   Js.log2("Not Melange, type error, not 2 arguments");
+  > #end
+  > EOF
+
+  $ melc x.ml
+  // Generated by Melange
+  'use strict';
+  
+  
+  console.log("It's Melange");
+  
+  /*  Not a pure module */
+