semantics

问题 Suppose we have the following instructions in Algol 68 and C, respectively: ref int x := 5; and (int*) x = 5; . What are their semantic difference?, it's the same?, because I think that the second one says something like "x will point to a constant" (it can't be compiled) and the first one says "x will point to a memory cell that points to another memory cell that contains a constant, 5". Is it correct?, if not, can you explain it a bit and give some examples to understand this? 回答1: I don't

问题 Suppose we have the following instructions in Algol 68 and C, respectively: ref int x := 5; and (int*) x = 5; . What are their semantic difference?, it's the same?, because I think that the second one says something like "x will point to a constant" (it can't be compiled) and the first one says "x will point to a memory cell that points to another memory cell that contains a constant, 5". Is it correct?, if not, can you explain it a bit and give some examples to understand this? 回答1: I don't

问题 Suppose we have the following instructions in Algol 68 and C, respectively: ref int x := 5; and (int*) x = 5; . What are their semantic difference?, it's the same?, because I think that the second one says something like "x will point to a constant" (it can't be compiled) and the first one says "x will point to a memory cell that points to another memory cell that contains a constant, 5". Is it correct?, if not, can you explain it a bit and give some examples to understand this? 回答1: I don't

问题 Suppose we have the following instructions in Algol 68 and C, respectively: ref int x := 5; and (int*) x = 5; . What are their semantic difference?, it's the same?, because I think that the second one says something like "x will point to a constant" (it can't be compiled) and the first one says "x will point to a memory cell that points to another memory cell that contains a constant, 5". Is it correct?, if not, can you explain it a bit and give some examples to understand this? 回答1: I don't

问题 I know as a fact, that we cant implement an IO monad independently, but I dont know why exactly. This code is an attempt to implement an imperative paradigm using functional language. Can you explain the difference between this example and true IO? It looks like function main implements the correct action order and remains lazy. import System.IO.Unsafe data Io a = Io a runIO :: Io a -> a runIO (Io a) = a instance Monad Io where return x = Io x Io a >>= f = f a -- internal side effect function

问题 I'm taking some predefined semantic rules and implementing them as an interpreter for the lettuce language using Scala. In Multi-Let, I'm trying to update an environment variable using two lists. I'm sort of new to Scala so I'm not too sure how to do this without converting the environment variable to a List. Is there a way to manipulate the return type in my zip function? I'm getting the following error message. My goal is to get a single updated map rather than a list of updated maps. cmd2

问题 I'm trying to figure out the most semantic way to markup something like this. John: blah blah Paul: blah blah George: blah blah Ringo: blah blah or John: blah blah Paul: blah blah George: blah blah Ringo: blah blah Ideally there'd be the CSS flexibility to do either or to break it into a paragraph with or without the names visible. I considered using the before: selector to add the names, but I also want them to be linkable. For example, I'd link to Ringo's twitter profile if he had one. It

问题 I'm trying to figure out the most semantic way to markup something like this. John: blah blah Paul: blah blah George: blah blah Ringo: blah blah or John: blah blah Paul: blah blah George: blah blah Ringo: blah blah Ideally there'd be the CSS flexibility to do either or to break it into a paragraph with or without the names visible. I considered using the before: selector to add the names, but I also want them to be linkable. For example, I'd link to Ringo's twitter profile if he had one. It

问题 I'm trying to figure out the most semantic way to markup something like this. John: blah blah Paul: blah blah George: blah blah Ringo: blah blah or John: blah blah Paul: blah blah George: blah blah Ringo: blah blah Ideally there'd be the CSS flexibility to do either or to break it into a paragraph with or without the names visible. I considered using the before: selector to add the names, but I also want them to be linkable. For example, I'd link to Ringo's twitter profile if he had one. It

问题 The void type in C seems to be strange from various different situations. Sometimes it behaves like a normal object type, such as int or char , and sometimes it just means nothing (as it should). Look at my snippet. First of all, it seems strange that you can declare a void object, meaning you just declare nothing. Then I created an int variable and casted its result to void , discarding it: If an expression of any other type is evaluated as a void expression, its value or designator is