[interpreter] Custom descriptor syntax #29

tlively · 2025-04-16T02:48:19Z

Add descriptor and describes clauses to the syntax of types. Update the
various operations on types accordingly, including text and binary
parsing and writing.

Add descriptor and describes clauses to the syntax of types. Update the various operations on types accordingly, including text and binary parsing and writing.

tlively · 2025-04-16T02:49:24Z

interpreter/custom/handler_name.ml

+                      let dt = match dt with
+                        | DescribesT (_, dt) -> dt
+                        | NoDescribesT dt -> dt in
+                      let ct = match dt with
+                        | DescriptorT (_, ct) -> ct
+                        | NoDescriptorT ct -> ct in
+                      ct) subtypes in


This pattern comes up a lot. Do you have a recommendation for a name and location for a helper function for this?

See suggestion for flattening the type.

tlively · 2025-04-16T02:50:27Z

interpreter/text/parser.mly

+described_type :
+  | str_type { fun c x -> NoDescriptorT ($1 c x) }
+  | LPAR DESCRIPTOR var str_type RPAR
+    { fun c x -> DescriptorT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }


Some of these lines are over 80 char long, but I'm not familiar with the formatting conventions. Is there a good automatic formatter I can run?

Yeah, formatting of the parser has become a real mess. I don't think there is a tool for auto-formatting mly files. Just follow some of the surrounding code and don't worry about it too much. I'll clean it up eventually. :)

rossberg · 2025-04-22T10:03:31Z

interpreter/syntax/types.ml

+and described_type =
+  | DescriptorT of heap_type * str_type
+  | NoDescriptorT of str_type
+
+and describing_type =
+  | DescribesT of heap_type * described_type
+  | NoDescribesT of described_type
+
+and sub_type = SubT of final * heap_type list * describing_type


I would suggest a more direct syntax, which simplifies pattern matching a lot:

Suggested change

and described_type =

| DescriptorT of heap_type * str_type

| NoDescriptorT of str_type

and describing_type =

| DescribesT of heap_type * described_type

| NoDescribesT of described_type

and sub_type = SubT of final * heap_type list * describing_type

and desc_type = DescT of heap_type option * heap_type option * str_type

and sub_type = SubT of final * heap_type list * desc_type

(We could turn the tuple into a record to avoid confusing the two clauses, but I suspect that will be tedious to use.)

rossberg · 2025-04-22T10:13:02Z

interpreter/syntax/types.ml

@@ -298,9 +316,13 @@ let unroll_def_type (dt : def_type) : sub_type =
  Lib.List32.nth sts i

 let expand_def_type (dt : def_type) : str_type =


I would expect that this has to return desc_type now, since the clauses affect a type's structure and become relevant in some operations. With the flat type representation suggested above, they can just be pattern-matched away where not needed.

(FWIW, I should rename str_type to comp_type here, to sync with the spec.)

rossberg · 2025-04-22T10:17:07Z

interpreter/text/parser.mly

+described_type :
+  | str_type { fun c x -> NoDescriptorT ($1 c x) }
+  | LPAR DESCRIPTOR var str_type RPAR
+    { fun c x -> DescriptorT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }


Yeah, formatting of the parser has become a real mess. I don't think there is a tool for auto-formatting mly files. Just follow some of the surrounding code and don't worry about it too much. I'll clean it up eventually. :)

rossberg · 2025-04-22T10:18:21Z

interpreter/text/parser.mly

+described_type :
+  | str_type { fun c x -> NoDescriptorT ($1 c x) }
+  | LPAR DESCRIPTOR var str_type RPAR
+    { fun c x -> DescriptorT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }


Suggested change

{ fun c x -> DescriptorT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }

{ fun c x -> DescriptorT (VarHT (StatX ($3 c type_).it), $4 c x) }

rossberg · 2025-04-22T10:18:49Z

interpreter/text/parser.mly

+describing_type :
+  | described_type { fun c x -> NoDescribesT ($1 c x) }
+  | LPAR DESCRIBES var described_type RPAR
+    { fun c x -> DescribesT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }


Suggested change

{ fun c x -> DescribesT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }

{ fun c x -> DescribesT (VarHT (StatX ($3 c type_).it), $4 c x) }

rossberg · 2025-04-22T10:20:02Z

interpreter/custom/handler_name.ml

+                      let dt = match dt with
+                        | DescribesT (_, dt) -> dt
+                        | NoDescribesT dt -> dt in
+                      let ct = match dt with
+                        | DescriptorT (_, ct) -> ct
+                        | NoDescriptorT ct -> ct in
+                      ct) subtypes in


See suggestion for flattening the type.

rossberg · 2025-04-22T10:23:34Z

interpreter/text/parser.mly

@@ -466,12 +466,22 @@ str_type :
  | LPAR ARRAY array_type RPAR { fun c x -> DefArrayT ($3 c) }
  | LPAR FUNC func_type RPAR { fun c x -> DefFuncT ($3 c) }

+described_type :
+  | str_type { fun c x -> NoDescriptorT ($1 c x) }
+  | LPAR DESCRIPTOR var str_type RPAR


I would have expected this, i.e., treating the clauses more like extra fields:

Suggested change

| LPAR DESCRIPTOR var str_type RPAR

| LPAR DESCRIPTOR var RPAR str_type

rossberg · 2025-04-22T10:23:43Z

interpreter/text/parser.mly

+
+describing_type :
+  | described_type { fun c x -> NoDescribesT ($1 c x) }
+  | LPAR DESCRIBES var described_type RPAR


Suggested change

| LPAR DESCRIBES var described_type RPAR

| LPAR DESCRIBES var RPAR described_type

[interpreter] Custom descriptor syntax

dbcdeee

Add descriptor and describes clauses to the syntax of types. Update the various operations on types accordingly, including text and binary parsing and writing.

tlively requested a review from rossberg April 16, 2025 02:48

tlively commented Apr 16, 2025

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rossberg reviewed Apr 22, 2025

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[interpreter] Custom descriptor syntax #29

[interpreter] Custom descriptor syntax #29

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tlively commented Apr 16, 2025

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tlively Apr 16, 2025

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rossberg Apr 22, 2025

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tlively Apr 16, 2025

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rossberg Apr 22, 2025

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rossberg Apr 22, 2025

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rossberg Apr 22, 2025

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		@@ -298,9 +316,13 @@ let unroll_def_type (dt : def_type) : sub_type =
		Lib.List32.nth sts i

		let expand_def_type (dt : def_type) : str_type =

	{ fun c x -> DescriptorT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }
	{ fun c x -> DescriptorT (VarHT (StatX ($3 c type_).it), $4 c x) }

	{ fun c x -> DescribesT ((fun y -> VarHT (StatX y.it)) ($3 c type_), ($4 c x)) }
	{ fun c x -> DescribesT (VarHT (StatX ($3 c type_).it), $4 c x) }

	\| LPAR DESCRIPTOR var str_type RPAR
	\| LPAR DESCRIPTOR var RPAR str_type

	\| LPAR DESCRIBES var described_type RPAR
	\| LPAR DESCRIBES var RPAR described_type

[interpreter] Custom descriptor syntax #29

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[interpreter] Custom descriptor syntax #29

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tlively commented Apr 16, 2025

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