[erlang-questions] List comprehension puzzler

Lloyd R. Prentice <>
Tue Sep 20 06:41:47 CEST 2016


Hi Hernando,

I came up with almost the exact same code after Dan Gudmunsson pointed out the error  of my ways.

Many thanks for the solution.

Best wishes,

Lloyd

Sent from my iPad

> On Sep 19, 2016, at 11:01 PM, Hernando Gisinger <> wrote:
> 
> Hello
> 
> 1> IsDigit = fun(C) -> C >= $0 andalso C =< $9 end.
> #Fun<erl_eval.6.52032458>
> 2> S = "123a456".
> "123a456"
> 3> [IsDigit(I) || I <- S].   
> [true,true,true,false,true,true,true]
> 
> 
> 2016-09-18 13:56 GMT-03:00 <>:
>> Hello,
>> 
>> Now this I would not expect:
>> 
>> 4> S = "123a456".
>> "123a456"
>> 
>> 5> is_integer(S).
>> false
>> 
>> 6> [is_integer(I) || I <- S].
>> [true,true,true,true,true,true,true]
>> 
>> Please tell me what I don't understand.
>> 
>> Many thanks,
>> 
>> LRP
>> 
>> 
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