[augeas-devel] [Augeas] #231: Set issue with recursive lens and indentation

[Augeas]

#231: Set issue with recursive lens and indentation
----------------------+-----------------------------------------------------
  Reporter:  raphink  |       Owner:  lutter
      Type:  defect   |      Status:  new   
  Priority:  major    |   Milestone:  next  
 Component:  Augeas   |     Version:  devel 
Resolution:           |    Keywords:        
----------------------+-----------------------------------------------------
Old description:

> I've tried to build recursive lenses a few times, and always end up with
> weird situations involving some kind of failure to match labels.
>
> Here is a simple example:
>
> {{{
> module Malformed =
>
>   let fix_kv (lns:lens) = [ key /[a-z]+/
>                           . ( (del /\./ "." . lns)
>                             | (del "=" "=" . store /[a-z]+/) ) ]
>
>   let rec kv = fix_kv kv
>
>   let lns = Util.indent . kv
>
>   test lns get "foo.bar=baz" = { "foo" { "bar" = "baz" } }
>
>   test lns put "foo.bar=baz" after
>      set "foo/bar" "faz" = ?
> }}}
>
> The get test works, but the set test fails with:
> {{{
> malformed.aug:13.2-14.28:exception thrown in test
> malformed.aug:13.7-14.24:exception: Failed to match
>     <<rec:{ /[a-z]+/ = /(([a-z]+))/ }>>
>   with tree
>     { "foo" }
>     Lens: malformed.aug:9.12-.28:
>     Error encountered at path
>
> Syntax error in lens definition
> Failed to load malformed.aug
> }}}
>
> When removing the Util.indent from lns, the lens works.

New description:

 I've tried to build recursive lenses a few times, and always end up with
 weird situations involving some kind of failure to match labels.

 Here is a simple example:

 {{{
 module Malformed =

   let fix_kv (lns:lens) = [ key /[a-z]+/
                           . ( (del /\./ "." . lns)
                             | (del "=" "=" . store /[a-z]+/) ) ]

   let rec kv = fix_kv kv

   let lns = Util.indent . kv

   test lns get "foo.bar=baz" = { "foo" { "bar" = "baz" } }

   test lns put "foo.bar=baz" after
      set "foo/bar" "faz" = ?
 }}}

 The get test works, but the set test fails with:
 {{{
 malformed.aug:13.2-14.28:exception thrown in test
 malformed.aug:13.7-14.24:exception: Failed to match
     <<rec:{ /[a-z]+/ = /(([a-z]+))/ }>>
   with tree
     { "foo" }
     Lens: malformed.aug:9.12-.28:
     Error encountered at path

 Syntax error in lens definition
 Failed to load malformed.aug
 }}}

 When removing the Util.indent from lns, the lens works:
 {{{
 Test result: malformed.aug:13.2-14.28:
 "foo.bar=faz"
 }}}

-- 
Ticket URL: <https://fedorahosted.org/augeas/ticket/231#comment:2>
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