On Sat, Oct 11, 2008 at 1:21 PM, Mark S. Miller <[EMAIL PROTECTED]> wrote:
> The let declaration is in. Like const and function declarations, it > has block-level letrec lexical scoping. I continue to oppose let > expressions and let statements, as they don't provide enough > additional power to justify their cost. For example, if lambda > supports optional args, as I think we all agree it should, then, > adapting a suggestion of Lars, we should define the scope in which the > default value expressions are evaluated so that > > var x = 2; > > (lambda (x = 3, y = x) (x+y))() Simplifying (lambda (x = 3, y = x) (x+y))() to just let (x = 3, y = x) (x+y) makes it much more clear when reading code what the intention of the programmer was. The reader doesn't need to interpret the code with as many steps and doesn't need to check at the end of the expression to see if the lambda is immediately called or not. This checking is an issue when an immediately called lambda spans more than a screen. Repeatedly writing the whole immediately-called, anonymous function is boilerplate for such a common pattern. I admit it is not much character boiler plate but it is the fact that the pattern is so common that I believe the concept is worth abstracting. It is the mental boilerplate that is the waste. Peter _______________________________________________ Es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
