8 Feb
2007
8 Feb
'07
10:49 a.m.
Hi
Also, due to the increasing popularity of witness types, I propose a optimization/pragmatic hint (warning, only 5 mins thought, please improve):
{-# NO_PATTERN_MATCHING #-}
does exactly what it says, and hints to the code generator that it can use 0 bytes to represent the value by some variation of the State# magic.
That pragma changes the semantics of the data type from being populated by _|_ and Proxy, to being populated by nothing. Pragma's should try not to change the semantics. Wouldn't a definition such as: data Proxy a Achieve the same effect? (Of course, we are still writing the Haskell 98 libraries, so we should just use normal data for now) Thanks Neil