When do you put double semicolons in F#?

Question

This is a stupid question. I\'ve been reading a couple books on F# and can\'t find anything that explains when you put ;; after a statement, nor can I find a pattern in the

Answer 1

There is no purpose for double semi-colons (outside of F# interactive). The semi-colon, according to MSDN:

• Separates expressions (used mostly in verbose syntax).
• Separates elements of a list.
• Separates fields of a record.

Therefore, in the first instance, ;; would be separating the expression before the first semi-colon from the empty expression after it but before the second semi-colon, and separating that empty expression from whatever came after the second semi-colon (just as in, say C# or C++).

In the instance of the list, I suspect you'd get an error for defining an empty list element.

With regards to the record, I suspect it would be similar to separating expressions, with the empty space between the semi-colons effectively being ignored.

F# interactive executes the entered F# on seeing a double semi-colon.

[Updated to cover F# interactive - courtesy of mfeingold)