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List.unsafe_tl, List.unsafe_hd #2919

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vicuna opened this issue Jul 8, 2004 · 1 comment
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List.unsafe_tl, List.unsafe_hd #2919

vicuna opened this issue Jul 8, 2004 · 1 comment
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feature-wish wontfix

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@vicuna
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vicuna commented Jul 8, 2004

Original bug ID: 2919
Reporter: administrator
Status: closed
Resolution: won't fix
Priority: normal
Severity: feature
Category: ~DO NOT USE (was: OCaml general)

Bug description

Full_Name: Evgeny Chukreev
Version:
OS:
Submission from: host134.t3n.sotline.ru (81.1.200.134)

It will be nice to have these functions in 3.08:
List.unsafe_tl ("%list_unsafe_tl")
List.unsafe_hd ("%list_unsafe_hd")

let unsafe_hd list : ('a list -> 'a) =
Obj.obj (Obj.field (Obj.repr list) 0))
and unsafe_tl list : ('a list -> 'a list) =
Obj.obj (Obj.field (Obj.repr list) 1))

  • works even slowly than List.hd and List.tl.
@vicuna vicuna closed this as completed Jul 8, 2004
@vicuna
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vicuna commented Jul 8, 2004

Comment author: administrator

From: sjah@land.ru

It will be nice to have these functions in 3.08:
List.unsafe_tl ("%list_unsafe_tl")
List.unsafe_hd ("%list_unsafe_hd")

Please, no!

If you really need it, here it is, with its consequence:

external hd : 'a list -> 'a = "%field0";;
hd [1;2];;
external tl : 'a list -> 'a list = "%field1";;
tl [1;2];;
hd [];;
Segmentation fault

Jacques

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@vicuna