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<tohoyn>in Gtk the constructors usually have return type GtkWidget. it would be could to have constructors having type of the constructed object as a result type.

<tohoyn>s/could/good/g

<tohoyn>the introspection library (Golf) has a flag for constructors

<tohoyn>but how to obtain the type to be constructed?

<daviid>tohoyn: (gtk-window-new 'toplevel) -| #<<gtk-window> 556143c74aa0>

<daviid>so does (make <gtk-window>)

<tohoyn>daviid: gtk-label-new returns <gtk-widget>

<tohoyn>daviid: AFAIK this is an usual convention in Gtk

<tohoyn>daviid: of course the dynamic type of the object is the type to be constructed

<daviid>(gtk-label-new "Bluefox") -| #<<gtk-label> 556143ca0940>

<tohoyn>daviid: yes

<tohoyn>daviid: I'm developing a programming language with static type declarations

<tohoyn>daviid: so it would be good if I could declare the return type of gtk-label-new to be <gtk-label>

<tohoyn>daviid: or have a constructor with different name for this

<tohoyn>daviid: of course it is possible to define this kind of constructors manually

<daviid>tohoyn: the 'type' is <gtk-label>

<mfg>Hi guile, i have a question regarding the following stackoverflow question: https://stackoverflow.com/questions/48559030/flatten-top-level-sublists-in-scheme

<mfg>the first answer gives an outline on how to solve that problem, but i seem to have an off-by-one error somewhere.

<mfg> https://dpaste.org/D78r is what i thought would be correct, but i have (() 1 2 3 (((4 . 3))) (5 (6)) . 7) as an result for the example given in the answer...

<mfg>so what did i do wrong here>

<mfg>?

<RhodiumToad>you want to flatten just one level?

<mfg>exactly

<mfg>well at least i think i want that, i'm not a schemer, so there might be a better solution for my problem... i'm trying to get this:

<mfg>("cc_library_headers"

<mfg> (("name" "libcutils_headers")

<mfg> (("vendor_available" #t)

<mfg> (("recovery_available" #t)

<mfg> (("host_supported" #t)

<mfg> (("export_include_dirs" ("include"))))))))

<mfg>into one list, but flattening destroys the sublists which i don't want

<RhodiumToad>why is that adding a nesting level each time?

<mfg>it is generated by a parser and the grammar rule is right recursive

<RhodiumToad>hm

<RhodiumToad>and the result you want is ("cc_library_headers" ("name" "libcutils_headers") ("vendor_available" #t) ...) ?

<mfg>yes, that is my goal

<RhodiumToad>or in short, (1 (2 (3 (4 (5))))) becomes (1 2 3 4 5)

<mfg>with numbers it should look that way yes

<RhodiumToad>how about (let loop ((lst lst)) (cond ((and (pair? lst) (pair? (cdr lst))) (cons (car lst) (loop (cadr lst)))) (#t lst)))

<RhodiumToad>or the equivalent with (match)

<RhodiumToad>or

<RhodiumToad>(define (unnest-right lst) (match lst ((h t) (cons h (unnest-right t))) (x x)))

<RhodiumToad>I think your question was not well stated

<mfg>what is your difficulty with my question? i'll try to clarify :)

<RhodiumToad>the question you asked didn't seem to have anything to do with the example you just showed above

<RhodiumToad>the code I gave is for the example above, not for the original question

<mfg>the original question arose, because i tried to solve what i showed in the example. i thought i could recursively take the car of such a nested list and flatten it one level after each recursion step

<mfg>but i didn't get the flattening right

<mfg>i don't even know about match :D, i have seen it in code but i never looked it up (it's the first time i'm using guile)

<RhodiumToad>needs (use-module ((ice-9 match)))

<RhodiumToad>er, use-modules

<mfg>i noticed that, it seems to work. that means i really have to read the documentation about it :D

<mfg>thanks for your help :)

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2020-03-16.log