[erlang-questions] questions about ERLANG!
Serge Aleynikov
saleyn@REDACTED
Sat Mar 28 13:14:31 CET 2009
Little addition to Hynek's advice - once you master the recursive
solution, you can search through the lists module and find this helpful
lists:sum/1 function:
1> lists:sum(lists:seq(1,10)).
55
Kid Erlang wrote:
> hi everybody. I have just discovered Erlang! it is very exciting. I
> have been making scripts with perl that call each other so I have
> hundreds of scripts running at once. my friend told me Erlang has
> processes so I thought I could replace my scripts with Erlang! I had
> bought the book programming Erlang. very good book and fun to read, but
> I still have questions about Erlang! it is my first functinal language
> and so far that has been pretty confusing! I am still reading the book too.
>
> recursive blew my mind! I have tried forever on this code and I finally
> have it working. there are no for loops in erlang so I had to write my
> own into recursive. here is the program what I came up with:
>
> -module(adder).
> -compile(export_all).
>
> add_up_list(List)->LengthOfList=erlang:length(List)-1,for_loop(0,LengthOfList,List).
> for_loop(CurrentLocationInList,LengthOfList,List)->if
> CurrentLocationInList==LengthOfList
> true->0;false->lists:nth(CurrentLocationInList+1,List)+for_loop(CurrentLocationInList+1,LengthOfList,List).
>
> the goal of this program is to take all the numbers of the list and add
> them together. but it will not compile! here is the error:
>
> ~$ erlc adder.erl
> ./adder.erl:5: syntax error before: true
> ./adder.erl:4: function for_loop/3 undefined
>
> where is my program wrong? I have written programs before this and they
> compiled. but this one really stumps me. I cannot figure out what is
> wrong.
>
> I have not got to the paralell part of Erlang yet but I hear it lets you
> automagically scale into the cloud! that is my goal with Erlang!
>
> - Kid Erlang
>
>
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