[英]Ocaml representation of values - Atoms
I looked at the internal representation of some OCaml values. 我查看了一些OCaml值的内部表示。 The representation of an empty array is an
atom(0)
, ie a block with tag=0
and size=0
. 空数组的表示是
atom(0)
,即tag=0
且size=0
。 Empty arrays of floats are represented by an atom(0)
too. 空的浮点数也由
atom(0)
表示。
Is there any OCaml value represented by an atom with tag > 0
? 是否有任何OCaml值由
tag > 0
的原子表示? If not: for what purpose the OCaml bytecode set contains the ATOM n
instruction? 如果不是:为什么OCaml字节码集包含
ATOM n
指令?
A tag > 0 is used for constructors with arguments, which would make them not atoms. 标签> 0用于带参数的构造函数,这将使它们不是原子。 Constructors without arguments on the other hand are stored as int instead of blocks so again not atoms.
另一方面,没有参数的构造函数存储为int而不是块,因此也不是原子。 So I think atom(0) is not used.
所以我认为不使用atom(0)。 Except ...
除了 ...
What about having a constructor with inline record that is empty? 如果构造函数的内联记录为空?
# type t = A of int | B of { };;
Error: Syntax error
Seems empty records are not allowed. 似乎不允许空记录。 I can't think of another way to create a 0 size block with tag other than creating such a block directly.
除了直接创建这样的块之外,我想不出用标签创建0大小块的另一种方法。 But that wouldn't be using the ATOM instruction.
但那不会使用ATOM指令。
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