#2200: big static random access arrays
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Reporter: jsnx | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler
Version: 6.8.2 | Severity: normal
Keywords: static array | Testcase:
Architecture: Multiple | Os: Multiple
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These would be unlike `StorableArray`s because they would be available at
compile time, and would be pure values. They would amount to arrays of
bytes, of course, but it'd be nice if they could be `(Storable a) =>
StaticArray a` and we could walk down them or randomly access them to get
the `a` values out of them. They should be capable of storing hundreds of
thousands of `Int`s.
What are some functions that work on these arrays? We need just one:
{{{
indexInto :: (Storable a) => StaticArray a -> Word -> a
}}}
Then we can make a `Monad` to walk up and down the array. It will be some
`State` hybrid. No `IO`. A bright person could implement static `Trie`s,
`RoseTree`s and other things using this `Monad` -- storing the offsets
mixed in with the data in an unholy mess and skipping forward or backward,
leveraging "the world’s most beautiful imperative language."
It's been suggested (SamB) that this should be implemented in Template
Haskell.
Important features of this array relative to other arrays and lists in
Haskell:
Specificity of Index::
A machine `Word` since that contains the finest grained pointer. When
indexing into a `Storable a`, the index is multiplied by `sizeOf
(undefined :: a)`.
Static Nature::
Exists to facilitate large static constants. The array does not support
any append or delete operations, there is no way to change any of its
values and it can not be copied.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2200>
GHC <http://www.haskell.org/ghc/>
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