Non-monolithic version of 'sequence' for IO monad?

Marcin 'Qrczak' Kowalczyk qrczak@knm.org.pl
Tue, 6 Nov 2001 00:09:58 +0000 (UTC)


Mon, 05 Nov 2001 14:23:18 -0800, Joe English <jenglish@flightlab.com> pisze:

> Is there any way, short of using unsafePerformIO,
> to implement a combinator
> 
>     f :: [IO a] -> IO [a]
> 
> in a way that the the result is produced lazily?

No. If evaluation of list elements causes IO, then it's unsafe.

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