Hi everyone, So I've taken a stab at implementing SRFI-89, using Guile's existing (ice-9 optargs) module -- my thinking was that the two were similar enough to make it worthwhile to have optargs do most of the heavy lifting. What I've done is add some pre-parsing of the formals list before it's passed to (ice-9 optargs)'s lambda* and some accommodation of incompatible behavior. Specifically:
* The (ice-9 optargs) module requires that the #optionals section, if present, come before the #keywords section, whereas SRFI-89 allows its corresponding sections to be in either order. * (ice-9 optargs) requires that non-optional positional formals be specified before any optional positional or keyword formals. * (ice-9 optargs) (and, apparently, Common Lisp) adds all the keyword arguments to the rest argument at call time. * SRFI-89 doesn't allow duplicate keyword arguments in a function call. * SRFI-89 keyword definitions allow the value of a keyword argument to be bound to a variable with a different name than the keyword; (ice-9 optargs) does not. I think that's everything -- except for one last quirk of (ice-9 optargs) that I discovered last night and am having trouble working around. It looks like when you've defined a function that takes traditional/required as well as keyword arguments, you need to pass all of the required arguments before passing any of the keyword ones. For example: (define* (g a #:key (b #f) #:rest r) (list a b r)) (g 1 #:b 2 3) => (1 2 (3)) ...but (g #:b 2 1 3) => (#:b #f (2 1 3)) The docs sort of hint at why this is implemented the way it is, but I think it eliminates a lot of the flexibility that keyword arguments buy you in the first place. What I want to know is whether this seems to you like a shortcoming in (ice-9 optargs) that ought to be fixed, or whether I should just ditch my implementation and go with the vanilla SRFI-89 implementation included with the specification. I've attached the draft I've been working on in case anyone wants to have a look. Regards, Julian
srfi-89.scm
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srfi-89.test
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