究竟什么是『指称语义』？
译自：What are denotations, exactly? 。除非特殊声明，文中「我」指原文作者 Oleg Kiselyov。 指称语义通常被描述为：利用数学对象解释表达式（语法对象）。那么，所谓『数学对象』究竟是什么？OCaml 代码可以是数学对象吗？花些时间去思考到底什么是指称语义是值得的。 在最早一批的诸多『指称语义』的定义中，Landin 指出（Landin 1966，第 8 节） The commonplace expressions of arithmetic and algebra have a certain simplicity that most communications to computers lack. In particular, (a) each expression has a nesting subexpression structure, (b) each subexpression denotes something (usually a number, truth value or numerical function), (c) the thing an expression denotes, i.e., its `value’, depends only on the values of its subexpressions, not on other properties of them....