list comprehension compilation

Bjorn Gustavsson <>
Tue Aug 1 15:43:13 CEST 2006


Thomas Raes <> writes:

> Compiling code that contains list comprehensions with lots of variables
> seems to take a long time on my system.
> For example, compiling the following code takes more than 4 minutes:
> 
> test() ->
>   
> [[X1,X2,X3,X4,X5,X6,X7,X8,X9,X10,X11,X12,X13,X14,X15,X16,X17,X18,X19,X20] ||
>         X1 <- [0],X2 <- [0],X3 <- [0],X4 <- [0],X5 <- [0],X6 <- [0],X7
> <- [0],X8 <- [0],X9 <- [0],X10 <- [0],
>         X11 <- [0],X12 <- [0],X13 <- [0],X14 <- [0],X15 <- [0],X16 <-
> [0],X17 <- [0],X18 <- [0],X19 <- [0],X20 <- [0]].

Guess that you are first one to have use so many generators.

I have now corrected the performance bug; the correction will be included
in R11B-1.

> However, when I enter this code at the erl-prompt, it evaluates immediately.

The shell does not use the compiler for evaluating expressions.

/Bjorn
-- 
Björn Gustavsson, Erlang/OTP, Ericsson AB



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