pass Core.Zone.local to Time.to_sec_string in log_entry

[stu-art]

I received

Error: This expression has type zone:Core.Zone.t -> bytes                                        
       but an expression was expected of type bytes  

When entering the log_entry definition into utop. After some discussion in the #ocaml freenode room, this fixes the issue.

[khanjehanzeb]

Can anyone explain the reason why we have to pass Core.zone.local ?

[agarwal]

Can anyone explain the reason why we have to pass Core.zone.local ?

The resulting string will differ depending on the timezone, so what timezone should be assumed if you didn't have to pass this argument. You can't just assume local timezone because maybe you're generating a webpage and want to show the string in the user's timezone, rather than that of the server.

[khanjehanzeb]

so in the book there was a typo in the example ?

[agarwal]

I see what you mean. The API of Core has changed since the book was published. I just checked the older version of to_sec_string, and indeed it doesn't take a timezone argument. That's not very flexible, so I guess they improved the function since then.

[OldPanda]

Here's a SO answer explaining this https://stackoverflow.com/a/34224843/2191173

[sharno]

The API of Core has changed again:
https://ocaml.janestreet.com/ocaml-core/v0.9/doc/core/Core__/Core_time_float/Zone/index.html

val local : t Core__.Import.Lazy.t

so passing local is not a solution for version 0.9 of Core
I think it's better just to use to_string instead

[teohhanhui]

Or use:

Time.to_sec_string ~zone:Time.Zone.utc time