源頭

睡前看《Denotational Semantics》前面的序，是 Scott 為 Strachey 寫的小傳。讀著讀著看到這一段：

On his work at Cambridge, Strachey also commented: "From about 1962 until 1966 [I] was engaged with several collaborators at Cambridge and London on the design of a general purpose programming language which came to be known as CPL [...]"

The influence of CPL was remarkable, however, and an implementation of a variant of CPL, devised by Strachey's student Martin Richards and called BCPL [...]

看到這裡我就叫出來了 ─ BCPL！剛剛看到 CPL 的時候怎麼沒想到呢？這大概是我最先知道的一個老語言。原因無他：

Clearly, C++ owes much to C. Except for closing a few serious loopholes in the type system, C is retained as a subset. I also retained C’s emphasis on facilities that are low-level enough to cope with the most demanding systems programming tasks. C in turn owes much to its predecessor BCPL; in fact, BCPL’s // comment convention was (re)introduced in C++. [...]

這是從我第一本正經的 CS 書《The C++ Programming Language》抄下來的。長久以來 BCPL 一直是我心裡 C family tree 最上面的 root node，突然又在它上面接 predecessor 還挺震撼的 XD。

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太炫了！