diff --git a/src/reason-parser/reason_heuristics.mli b/src/reason-parser/reason_heuristics.mli
new file mode 100644
index 000000000..39f7ca673
--- /dev/null
+++ b/src/reason-parser/reason_heuristics.mli
@@ -0,0 +1,16 @@
+open Ppxlib
+
+val is_punned_labelled_expression : expression -> string -> bool
+val isUnderscoreIdent : expression -> bool
+val isUnderscoreApplication : expression -> bool
+val melExprCanBeUncurried : expression -> bool
+val isPipeFirst : expression -> bool
+val isPipeFirstWithNonSimpleJSXChild : expression -> bool
+val singleTokenPatternOmmitTrail : string -> bool
+
+val funAppCallbackExceedsWidth :
+   printWidth:int
+  -> args:(arg_label * expression) list
+  -> funExpr:expression
+  -> unit
+  -> bool