[erlang-questions] How to make this work

[Roelof Wobben]

I think I have a too old version because I see this :

exception error: undefined function erlang:monotonic_time/0 in function 
my_time:time_spend/1 (my_time.erl, line 6)

I have R16B03,

Roelof



Op 12-8-2015 om 17:47 schreef Roelof Wobben:
> Correct but my question is how I can access the function with a fun.
>
> Roelof
>
>
> Op 12-8-2015 om 17:39 schreef Dmitry Kolesnikov:
>> Hello,
>>
>> You can use built-in function
>> http://erldocs.com/17.0/stdlib/timer.html?i=0&search=timer:tc#tc/1
>>
>> You can also check from OTP source the implementation of this 
>> function and compare it with your's
>> https://github.com/erlang/otp/blob/maint/lib/stdlib/src/timer.erl#L160
>>
>> It gives you hints :-)
>>
>> Best Regards,
>> Dmitry
>>
>>> On 12 Aug 2015, at 18:34, Roelof Wobben <r.wobben@REDACTED> 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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>
>
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