unikernel/duniverse/ppxlib/test/ppxlib-pp-ast/json.t

@@ -0,0 +1,118 @@
+ppxlib-pp-ast as a --json flag that pretty prints the AST in JSON format.
+
+Consider the following .ml file:
+
+  $ cat > test.ml << EOF
+  > let x = 2
+  > let y = true
+  > let z =
+  >  fun x ->
+  >  x
+  > EOF
+
+This is how it's printed without the flag:
+
+  $ ppxlib-pp-ast test.ml
+  [ Pstr_value
+      ( Nonrecursive
+      , [ { pvb_pat = Ppat_var "x"
+          ; pvb_expr = Pexp_constant (Pconst_integer ( "2", None))
+          ; pvb_constraint = None
+          ; pvb_attributes = __attrs
+          ; pvb_loc = __loc
+          }
+        ]
+      )
+  ; Pstr_value
+      ( Nonrecursive
+      , [ { pvb_pat = Ppat_var "y"
+          ; pvb_expr = Pexp_construct ( Lident "true", None)
+          ; pvb_constraint = None
+          ; pvb_attributes = __attrs
+          ; pvb_loc = __loc
+          }
+        ]
+      )
+  ; Pstr_value
+      ( Nonrecursive
+      , [ { pvb_pat = Ppat_var "z"
+          ; pvb_expr =
+              Pexp_function
+                ( [ { pparam_loc = __loc
+                    ; pparam_desc = Pparam_val ( Nolabel, None, Ppat_var "x")
+                    }
+                  ]
+                , None
+                , Pfunction_body (Pexp_ident (Lident "x"))
+                )
+          ; pvb_constraint = None
+          ; pvb_attributes = __attrs
+          ; pvb_loc = __loc
+          }
+        ]
+      )
+  ]
+Now how it's printed with the flag:
+
+  $ ppxlib-pp-ast --json test.ml
+  [
+    {
+      "Pstr_value": [
+        "Nonrecursive",
+        [
+          {
+            "pvb_pat": { "Ppat_var": "x" },
+            "pvb_expr": {
+              "Pexp_constant": { "Pconst_integer": [ "2", "None" ] }
+            },
+            "pvb_constraint": "None",
+            "pvb_attributes": "__attrs",
+            "pvb_loc": "__loc"
+          }
+        ]
+      ]
+    },
+    {
+      "Pstr_value": [
+        "Nonrecursive",
+        [
+          {
+            "pvb_pat": { "Ppat_var": "y" },
+            "pvb_expr": { "Pexp_construct": [ { "Lident": "true" }, "None" ] },
+            "pvb_constraint": "None",
+            "pvb_attributes": "__attrs",
+            "pvb_loc": "__loc"
+          }
+        ]
+      ]
+    },
+    {
+      "Pstr_value": [
+        "Nonrecursive",
+        [
+          {
+            "pvb_pat": { "Ppat_var": "z" },
+            "pvb_expr": {
+              "Pexp_function": [
+                [
+                  {
+                    "pparam_loc": "__loc",
+                    "pparam_desc": {
+                      "Pparam_val": [ "Nolabel", "None", { "Ppat_var": "x" } ]
+                    }
+                  }
+                ],
+                "None",
+                { "Pfunction_body": { "Pexp_ident": { "Lident": "x" } } }
+              ]
+            },
+            "pvb_constraint": "None",
+            "pvb_attributes": "__attrs",
+            "pvb_loc": "__loc"
+          }
+        ]
+      ]
+    }
+  ]
+
+You can compase with other flags, for example --show-locs to display location: