>
> I'm puzzled by the stuff inside the stack-effect syntax: "( -- )".
>
> I thought that the tokens on either side of the "--"
>
> are just dummy variables representing, on the one hand, *strictly*
>
> the *number of input arguments and the number of results*, and, on the
> other,
>
> *loosely* the types of those arguments and results. I must not have the
>
> right idea. How can per-stack-position type-integrity be enforced if
>
> this is so?
>
> For the most part they are dumb, but within the desire for some convention.
Use the predicates if you feel something is out of control and the stack
isn't in the right order. If you want something to work from the class or
an instance, you will see conversion at time.
TUPLE: jim ;
ERROR: not-jim x ;
: only-clones ( x -- x ) dup jim? [ not-jim ] unless ;
! try each seperately
jim only-clones
jim new only-clones
"jim" only-clones
This seems to be the kind of type checking you are looking for. It's a
little, in a stockyard, like checking each cow for cowness as it walks
around, rather than as it was admitted. Maybe use it in the beginning, but
sooner or later trust your own code more
>
>
>
> --
>
> ( scratchpad ) : foo ( x quot: ( x -- ) -- ) call ; inline
>
> ( scratchpad ) : bar ( x y -- ) [ + . ] foo ;
>
> ! "bar" should cause an "Input quotation to foo doesn't match its
>
> expected effect" error
>
> --
>
>
>
> I don't understand above what "quot:" and more generally what "x quot: ( x
> -- )"
>
> as the before-effect of foo is doing. The colon on the right side of
> "quot:" is
>
> confusing me, because I am trying to read RPN, left to right. This syntax
>
> makes me want to reverse my reading direction for that expression. I can't
>
> find any info in Browser on "quot:".
>
>
>
>
>
> If the word declares a polymorphic effect (using "..a" style stack
>
> variables to represent a variable number of values), the arities of
>
> the stack variables will be unified, and an error raised if
>
> unification fails:
>
>
>
> Does "Unification" mean "arities of stack variables are determined to be
> equal"?
>
> There is a section in Browser called "Stack effect checking". What should
> I read
>
> besides this to understand the full significance of the stack-effect
> syntax, what
>
> it can do and not do, and how it affects compiler behavior?
>
>
>
>
>
> --
>
> ( scratchpad ) \ if see
>
> : if ( ..a ? true: ( ..a -- ..b ) false: ( ..a -- ..b ) -- ..b )
>
> ? call ;
>
> ( scratchpad ) : bas ( x y z? -- ) [ + ] [ neg ] if ;
>
> ! "bas" should cause an "Input quotations to “if” don't match their
>
> expected effects" error
>
> --
>
> I'm not understanding the English in the comment above. Ditto for the
>
> similar comment above. The quotes are matched, but I cannot make any sense
>
> of it.
>
>
>
> If a higher-order word declares no stack effect for its quotation
>
> arguments, the overall stack effect of the caller will still be
>
> checked when the body of the higher-order word and its arguments have
>
> been inlined.
>
>
>
> That makes sense, but I need to study a full description of the
> stack-effect syntax
>
> and it ramifications for thinking about the effects of higher-order words.
>
>
>
>
>
> Shaping
>
>
> ------------------------------------------------------------------------------
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>
>
--
Jim
"I'm for extending the working Medicare program for our seniors all the way
back to contraception, so Americans can concentrate on living their lives
without fear of changing a job, going bankrupt from deductibles or fighting
HMO bureaucracy."
------------------------------------------------------------------------------
Beautiful is writing same markup. Internet Explorer 9 supports
standards for HTML5, CSS3, SVG 1.1, ECMAScript5, and DOM L2 & L3.
Spend less time writing and rewriting code and more time creating great
experiences on the web. Be a part of the beta today
http://p.sf.net/sfu/msIE9-sfdev2dev
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