On Thu, Aug 8, 2013 at 11:05 PM, Tom Ellis < tom-lists-haskell-cafe-2013@jaguarpaw.co.uk> wrote:
On Thu, Aug 08, 2013 at 03:38:41PM +0200, Jerzy Karczmarczuk wrote:
One could simply implement IO as a free monad Interesting. I wonder how.
See [1] for an explanation of free monads in general. For IO in particular, define a functor
data IOF a = GetChar (Char -> a) | PutChar Char a | ...
with constructors for all elementary IO operations.
If I understand correctly, you're proposing equality of (IO a) based on the AST of imperatives, similar to what comes out of GCC's front-end for C [1]. In what way is this syntactical equality "reasonable"? Useful perhaps for detecting C&P coding from befuddled undergrads? [1] http://digitocero.com/es/blog/exportar-y-visualizar-el-arbol-sintactico-abst... -- Kim-Ee