Salut, c'est encore moi
Egalement je ne comprend pas pourquoi on appel ça la monade Maybe. Pour moi une monade c'est une encapsulation d'une suite d'opérations impératives... Or là je vois le Maybe comme un sorte d'algèbre sur les types: Maybe a c'est la "somme" de 2 types: "a" ou "rien".
About monads: A monad is just an algebraic structure having two neccesary operations: bind (>>=) and return . For an other example the set of real numbers R is a ring having operations like + and * . And 0 and 1 if you need them are also here. But we may want to use the support set of an algebraic structure withaout taking care what this structure is. Somebodi in finance for example don't know anything about rings and other structures but he /she uses numbers from R daily. That's the case of Maybe: The set {Maybe a | a <- any type} U {Nothing} can be seen as a monad BY DEFINING PROPER monadic operations. But we can use only the datatype to represent computable or uncomputable (Nothing) values. Need to use Maybe ? Use it ! It's defined. Dan Popa ____________________________________________________________________________________ Shape Yahoo! in your own image. Join our Network Research Panel today! http://surveylink.yahoo.com/gmrs/yahoo_panel_invite.asp?a=7