[Haskell-cafe] Re: Hugs vs GHC
(again)was: Re: Somerandomnewbiequestions
Benjamin.Rudiak-Gould at cl.cam.ac.uk
Wed Jan 12 18:52:04 EST 2005
Marcin 'Qrczak' Kowalczyk wrote:
>File positions are not evil. They allow to treat files and devices
>in a uniform way.
Indeed, file positions are exactly as evil as indices into shared memory
arrays, which is to say not evil at all. But suppose each shared memory
array came with a shared "current index", and there was no way to create
additional ones. Suppose you couldn't index the array by a local
variable: instead, you had to store the local variable into the shared
index register first, overwriting whatever was there before. If you only
wanted to use the array as a source or sink for a single stream, that
would be fine. In every other case, it would be awful. Even read-only
sharing would require the invention of some sort of cooperative locking
discipline, and if some process didn't respect the locking and couldn't
be changed, read-only sharing would become impossible. That's just silly.
The way to solve this problem is to decouple the index from the shared
memory array. You can easily simulate the single-index behavior if
that's what you want, but you also get a lot of additional functionality.
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