[commit: hoopl] simonmar-alternative-block-rep: More commentary on the new representation (d46106f)
Norman Ramsey <[email protected]>
| Newsgroups | gmane.comp.lang.haskell.cvs.libraries |
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| Message-ID | <[email protected]> |
Repository : ssh://darcs.haskell.org//srv/darcs/packages/hoopl On branch : simonmar-alternative-block-rep http://hackage.haskell.org/trac/ghc/changeset/d46106f684132b771dd14b001e4070cd5f1d7c4e >--------------------------------------------------------------- commit d46106f684132b771dd14b001e4070cd5f1d7c4e Author: Norman Ramsey <[email protected]> Date: Thu Jun 21 22:44:49 2012 +0200 More commentary on the new representation >--------------------------------------------------------------- src/Compiler/Hoopl/Graph.hs | 13 +++++++++---- 1 files changed, 9 insertions(+), 4 deletions(-) diff --git a/src/Compiler/Hoopl/Graph.hs b/src/Compiler/Hoopl/Graph.hs index b1464b3..96b4b64 100644 --- a/src/Compiler/Hoopl/Graph.hs +++ b/src/Compiler/Hoopl/Graph.hs @@ -51,16 +51,21 @@ data Block n e x where -- principles are easy to discern: -- -- --- - Fully open blocks are treated as lists of O/O nodes based on the +-- 1. Fully open blocks are treated as lists of O/O nodes based on the -- empty/singleton/append algebra. This representation gives -- append in constant time and allows either front or back bias. -- --- - Cons and snoc are such common cases that they are included to +-- 2. Cons and snoc are such common cases that they are included to -- reduce the number of indirections in the representations. -- --- - Anywhere a block is closed, the closing node is accessible in +-- 3. Anywhere a block is closed, the closing node is accessible in -- constant time. - +-- +-- The original representation rejected principle 3 but upheld principle 2. +-- The list model was more restrictive, supporting only append and singleton +-- but not empty. The original had an additional principle (4?) which said +-- that every singleton node should also be a block. We seem to have found +-- no need to preserve this principle. ------------------------------------------------------------------