I am converting several modules based on OCaml to F#. I have the code

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Asked: June 11, 20262026-06-11T01:05:21+00:00 2026-06-11T01:05:21+00:00

I am converting several modules based on OCaml to F#. I have the code

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I am converting several modules based on OCaml to F#. I have the code converted and running in F#, however the result of the final function in F# is not the same as the result of the final function in OCaml. So obviously I have to follow the function calls to figure out which function is returning the wrong result.

OCaml has a nice top-level directive for tracing the input and output of a function, i.e. #trace .

I have searched F#’s debug and trace methods and the closest I get is to instrument the code using Trace.Write methods but it takes several lines for each method.

e.g.

Original

let fun001 parm001 =
  parm001 * 10

Instrumented

let fun001 parm001 =
  // For VS 2010, this trace output will be sent to Output window.
  System.Diagnostics.Trace.WriteLine("function001 <--");      
  System.Diagnostics.Trace.WriteLine(sprintf "%A" parm001);      
  let result = parm001 * 10
  System.Diagnostics.Trace.WriteLine("function001 -->");
  System.Diagnostics.Trace.WriteLine(sprintf "%A" result);
  result

Does F# have the same functionality as OCaml #trace that I missed when searching?

If you are sure the answer is no, that’s all I need. I know people frown on short answers, but that is all I need if the answer is no.

EDIT

For more complex methods where capturing the result would evolve extensive modification to the code

Original

let func001 parm001 parm002 =
    match parm001 with
    | pattern001 -> func002 parm002
    | head :: tail -> 
        func003 head
        func001 tail
    | [] -> failwith "failed"

Instrumented

let func001org parm001 parm002 =
    match parm001 with
    | pattern001 -> func002 parm002
    | head :: tail -> 
        func003 head
        func001 tail
    | [] -> failwith "failed"
and fun001 parm001 parm002 =
  // For VS 2010, this trace output will be sent to Output window.
  System.Diagnostics.Trace.WriteLine("function001 <--");      
  System.Diagnostics.Trace.WriteLine(sprintf "%A, %A" parm001 parm002 );      
  let result = func001org parm001 parm002 
  System.Diagnostics.Trace.WriteLine("function001 -->");
  System.Diagnostics.Trace.WriteLine(sprintf "%A" result);
  result

EDIT

PostSharp does not support F#. See: Using PostSharp with F# – Need documentation with working example