ketil: > Aaron Tomb <[EMAIL PROTECTED]> writes: > > >> Huh? Type safety buys [...] nothing about dereferencing null > >> pointers, which are the moral equivalent of Nothing. > > > What type safety buys you, in my mind, is that Nothing is only a valid > > value for explicit Maybe types. In cases where you don't use Maybe, > > the "null" situation just can't occur. In languages with null > > pointers, any pointer could possibly be null. > > To write Haskell that is obviously safe, you need to check all cases > of algebraic data types - both Just and Nothing. > To do something similar in C, you need to check every pointer for NULL. > > The great thing about Maybe is that once I've checked it isn't > Nothing, I can extract the value and dispense with further checks. > > foo mbx = maybe default (bar x) mbx
And GHC will warn me when I forget to check all cases, and prevent me from compiling at all, if I don't do any check. -- Don _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
