Question

Why the code

if some_bool_var then
begin
    output_string some_file "some string";   (* <--- error here *)
end

generates “applied to too many arguments” error. But if I change it to

if some_bool_var then output_string some_file "some string";

it compiles fine.

Why is it so?
Thank you.

Answer 1

I’m pretty skeptical that what you’ve presented doesn’t compile. I copied it into the top level and sure enough I’m not getting an error at all.

The problem is most likely not what you’ve typed but what is after what you’ve typed. I’m guessing you’ve got more lines of code for this particular function, thus end should have a semi-colon after it denoting the end of that command. Think of begin ... end as an alternative to ( ... ), and ...; as an alternative to let () = ... in. Thus, using begin ... end is not a replacement for the use of a semicolon.

Also, the semi-colon that ends your output_string call between begin and end is unnecessary since that block does not continue with more commands.