|
Hi,
Just as we can define infix operators as syntactic sugar,
could we not also have a similar mechanism for programmable fancy
brackets?
There could be a keyword for the bracket declaration and a
function definition, in this way ana- and catamorphisms, Template Haskell-like
syntax, and set notation could become a regular feature of the language. I
am more interested in the general idea than the syntax of this specific
example:
\begin{code}
bracket (( _ )) :: a -> Ana a
bracket (| _ |) :: a -> Cata a
bracket [ _ | _ |] :: Char -> b
-> Splice -- or whatever
bracket {[ _ , .. ]} :: [a] -> SList a
((( _ ))) :: a -> Ana a
(( x )) = Ana x
((| _ |)) :: a -> Cata a
(| x |) = Cata x
([ _ | _ |]) :: Char -> b -> Splice
[ c | t |] = case c of
b
-> doC t
d
-> doD t -- or whatever
-- the idea of this bracket is to create a user-defined
list-type structure
-- {[ "the" , "lambda" , "calculus"
]}
-- would have the value
-- (SCons "the" (SCons "lambda" (SCons
"calculus" SEmpty)))
({[ _ , .. ]} :: [a] -> SList a
{[ [] ]} = sempty
{[ x:xs ]} = scons x {[ xs ]}
\end{code}
Any thoughts?
Vivian
|
_______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
