Fun with higher-order functions in C and Objective-C
The latest release of Mac OS X (Snow Leopard) came with an upgrade to the C and Objective-C languages, adding lambda abstractions — which they call blocks. Matt Gallagher has a nice blog post that describes some of the trickier aspects of blocks: http://cocoawithlove.com/2009/10/ugly-side-of-blocks-explicit.html
Interesting is the function 'newDoubleToIntComparison' (in Section "Declaring a block that returns a block"), which is a curried[1] version of 'compareDoubleToInt'. Together with the explicit memory management for returned blocks and the need for involved type annotations and casts, it becomes clear why functional languages like Haskell make curried functions the default as well as support garbage collection and type inference out of the box. [1] http://en.wikipedia.org/wiki/Currying
1 comment
Oct 20, 2009
Manuel Chakravarty said...
BTW, you can use blocks outside of Mac OS X by using either the clang C compiler or llvm-gcc.
