[erlang-questions] How to make this work

Siraaj Khandkar <>
Wed Aug 12 17:44:35 CEST 2015


The problem is exactly what the error message says - it is a syntax error.
The message says that the syntax error is before the symbol '->'.

1) Can you find all the places where you used that symbol in the above
example?
2) Now compare each one of your uses of '->' to examples in the tutorial
you're reading.
3) Are you using it _exactly_ the same as in the tutorial?
4) What is different?

Hint: I see 2 places to check.


On Wed, Aug 12, 2015 at 11:34 AM, Roelof Wobben <> wrote:

> Hello,
>
> Im trying this exercise from the programming erlang book.
>
> Look up the definitions of erlang:now/0, erlang:date/0, and erlang:time/0.
> Write a
> function called my_time_func(F), which evaluates the fun F and times how
> long it takes.
>
> So I did this :
>
> -module(my_time).
>
> -export( [time_spend/1] ).
>
> time_spend(F) ->
>     Begintime = time:now(),
>     F(3),
>     Endtime = time:now(),
>     Endtime - Begintime.
>
>
> but then when I do this in erl :
>
> 11> my_time:time_spend(fun x -> 2 * X end).
>  * 1: syntax error before: '->'
> 11> my_time:time_spend(Double = fun x -> 2 * X end).
> * 1: syntax error before: '->'
>
> how can I make this work ?
>
> Roelof
>
>
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