While quotations are sequences, in order for the stack-checker to infer the proper effect for combinators, you can't call append on two quotations, you must call compose instead. Likewise with suffix/prefix, you should call curry.For what I undertood and learned, "quotations" and "sequences" are equal when used as data, but quotations acted very differenct when used as codes.
"quotations" like anonymous function in function paradigm, are executable, so, in factor philosophy, they must be checked for stack effects when complied, that requirement ruled out the simple usage of sequence operation words on them.
But I wondered if simple usage of append is feasible in Syntax definition, that means there is no strong requirement of stack effect check when parsing and building the lexer?
Thanks.
To put it all together, look at a parse-time example, SYNTAX: definition: IN: syntax SYNTAX: SYNTAX: scan-new-word parse-definition define-syntax ; : parse-definition ( -- quot ) \ ; parse-until >quotation ; : define-syntax ( word quot -- ) [ drop ] [ define ] 2bi t "parsing" set-word-prop ;What's happening here is that, at parse-time, you create a new word, parse its definition until the semi-colon, and then convert that into a quotation. So all your suffix! and append! are really creating an array of code at parse-time and then, since converting between sequence types makes sense, you convert that array to a quotation. Since this happens at parse-time, it's safe to do this--you do not need compose/prepose and curry. Finally, setting the "parsing" property tells the parser that your new SYNTAX: is a parsing word.I hope this helps, and please ask any followup questions! Doug ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Factor-talk mailing list Factor-talk@lists.sourceforge.net <mailto:Factor-talk@lists.sourceforge.net> https://lists.sourceforge.net/lists/listinfo/factor-talk ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Factor-talk mailing list Factor-talk@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/factor-talk
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