* "define-constant is only allowed in a <body>"
@ 2022-11-19 14:37 Panicz Maciej Godek
2022-11-20 22:41 ` Per Bothner
0 siblings, 1 reply; 3+ messages in thread
From: Panicz Maciej Godek @ 2022-11-19 14:37 UTC (permalink / raw)
To: kawa
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I have a module named (mapping), which contains a thing that I have called
"mapping", which is a nice functional interface to mutable hash tables
(based on SRFI-17):
https://github.com/panicz/grasp-android/blob/master/stages/retreat/GRASP/src/mapping.scm
Therein, you can also find the following definition of define-mapping:
(define-syntax-rule (define-mapping (mapping-name key) default-value)
(define-early-constant mapping-name
(mapping (key) default-value)))
where define-syntax-rule is defined in a straightforward way in another
module.
When I try to use this code from yet another module -- more specifically,
this one:
https://github.com/panicz/grasp-android/blob/master/stages/retreat/GRASP/src/panel.scm#L130
as
(define-mapping (on-key-press code) never)
I get the error message
define-constant is only allowed in a <body>
but when I use the expanded version
(define on-key-press (mapping (code) never))
everything works.
I wonder what could be the reason of Kawa's behavior.
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: "define-constant is only allowed in a <body>"
2022-11-19 14:37 "define-constant is only allowed in a <body>" Panicz Maciej Godek
@ 2022-11-20 22:41 ` Per Bothner
2022-11-20 23:29 ` Panicz Maciej Godek
0 siblings, 1 reply; 3+ messages in thread
From: Per Bothner @ 2022-11-20 22:41 UTC (permalink / raw)
To: Panicz Maciej Godek, kawa
On 11/19/22 06:37, Panicz Maciej Godek via Kawa wrote:
> When I try to use this code from yet another module -- more specifically,
> this one:
>
> https://github.com/panicz/grasp-android/blob/master/stages/retreat/GRASP/src/panel.scm#L130
>
> as
>
> (define-mapping (on-key-press code) never)
>
> I get the error message
>
> define-constant is only allowed in a <body>
>
> but when I use the expanded version
>
> (define on-key-press (mapping (code) never))
>
> everything works.
>
> I wonder what could be the reason of Kawa's behavior.
Kawa is presumably complaining that the define-early-constant is
in a non-<body> context.
This is allowed:
(begin (define-early-constant ...) ...)
This is not:
(list (define-early-constant ...) ...)
One of the problems with Scheme S-expression-based syntax is that
it is sometimes tricky to tell what parenthesis does what.
For example, it is easy to end up with this after some macro-expansion:
((define-early-constant ...))
--
--Per Bothner
per@bothner.com http://per.bothner.com/
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: "define-constant is only allowed in a <body>"
2022-11-20 22:41 ` Per Bothner
@ 2022-11-20 23:29 ` Panicz Maciej Godek
0 siblings, 0 replies; 3+ messages in thread
From: Panicz Maciej Godek @ 2022-11-20 23:29 UTC (permalink / raw)
To: Per Bothner; +Cc: kawa
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niedz., 20 lis 2022 o 23:41 Per Bothner <per@bothner.com> napisał(a):
>
>
> On 11/19/22 06:37, Panicz Maciej Godek via Kawa wrote:
> > When I try to use this code from yet another module -- more specifically,
> > this one:
> >
> >
> https://github.com/panicz/grasp-android/blob/master/stages/retreat/GRASP/src/panel.scm#L130
> >
> > as
> >
> > (define-mapping (on-key-press code) never)
> >
> > I get the error message
> >
> > define-constant is only allowed in a <body>
> >
> > but when I use the expanded version
> >
> > (define on-key-press (mapping (code) never))
> >
> > everything works.
> >
> > I wonder what could be the reason of Kawa's behavior.
>
> Kawa is presumably complaining that the define-early-constant is
> in a non-<body> context.
>
> This is allowed:
> (begin (define-early-constant ...) ...)
>
> This is not:
> (list (define-early-constant ...) ...)
>
> One of the problems with Scheme S-expression-based syntax is that
> it is sometimes tricky to tell what parenthesis does what.
> For example, it is easy to end up with this after some macro-expansion:
>
> ((define-early-constant ...))
>
>
I understand this message the way you explained it
-- it just doesn't make sense in my context.
There seems to be an issue with module dependency resolution.
The problematic expansion was in the (panel) module.
It contains a dependency on the (mapping) module.
The main module (either grasp-terminal.scm or grasp-desktop.scm)
included (import (panel)), and the compilation failed with the above
message.
But when I add (import (mapping)) to the main module -- before the
(import (panel)) clause -- the compilation succeeds. (However, if I add it
after (import (panel)) -- it still breaks).
I realized that I ran into that problem early on during my work,
but instead of reporting it, I just started including module dependencies
transitively in the "right order". This is a workaround, but I think
that there might be some issue between reflection, macro expansion
and module dependency loading.
I'll let you know if I manage to find a minimal set of modules which break
in this way.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-11-20 22:41 ` Per Bothner
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