Added a regression test for F#

sample_files/compare.expected

@@ -64,6 +64,9 @@ sample_files/elvish_before.elv sample_files/elvish_after.elv
 sample_files/erlang_before.erl sample_files/erlang_after.erl
 c4a48cdd69bc3d0ef5e6bf2e5a8424f9  -
 
+sample_files/f_sharp_before.fs sample_files/f_sharp_after.fs
+a22c0257a72bb07fc3f005638ea95952  -
+
 sample_files/hack_before.php sample_files/hack_after.php
 f4e6a08cf167ed376dac629bead4e54d  -
 

sample_files/f_sharp_after.fs

@@ -0,0 +1,22 @@
+namespace X
+
+open System
+open System.IO
+
+type A = 
+    | A of int
+    | B of string
+
+type Record = { 
+    A : string
+    B : int
+}
+
+module M =
+
+    let f y = y + 1
+
+    let list = [
+        "a"
+        "b"
+    ]

sample_files/f_sharp_before.fs

@@ -0,0 +1,13 @@
+namespace X
+
+open System
+
+type A = A of int
+
+type Record = { A : string }
+
+module M =
+
+    let f x = x + 1
+
+    let list = []