在这段clojure代码中：
(defn makeStructs ;line 27
"open fName as a file and turns each line into a struct. Returns a Vector of structs"
[fName]
with-open[r (reader (file fName))]
(let [r
res (doall (map makeStruct (line-seq r)))
]
(. r close)
res
)
)
我收到此编译器错误：
Exception in thread "main" java.lang.Exception: Can't take value of a macro: #'clojure.core/with-open (clojureHW.clj:27)
第27行在上面评论。
知道问题是什么吗？
你需要实际调用宏，
(defn makeStructs ;line 27
"..."
[fName]
(with-open ; note the extra paren
(defn makeStructs ;line 27
"open fName as a file and turns each line into a struct. Returns a Vector of structs"
[fName]
with-open[r (reader (file fName))]
(let [r
res (doall (map makeStruct (line-seq r)))
]
(. r close)
res
)
)
这不能工作，因为
with-open。这将是一个正常的符号，它不被称为。您的let中的表单数量不一致。你有r，res aund（doall ...）。你已经在with-open中为'r'做了正确的绑定。所有你需要的是
（让[res（doall（map makeStruct（line-seq r）））] ....）
你为什么这样做 (. r close) with-open宏可以在这里看到： http://clojuredocs.org/clojure_core/clojure.core/with-open
所以你得到：
(defn makeStructs
"open fName as a file and turns each line into a struct. Returns a Vector of structs"
[fName]
(with-open [r (reader (file fName))]
(let [res (doall (map makeStruct (line-seq r)))]
res)))
但是因为你只有一件事让你不需要：
(defn makeStructs
"open fName as a file and turns each line into a struct. Returns a Vector of structs"
[fName]
(with-open [r (reader (file fName))]
(doall (map makeStruct (line-seq r)))))
Lisp语言非常简单，大多数程序员只是想让自己变得困难，因为他们已经习惯了。你遇到的很多问题都是因为你已经习惯了像X这样的工作，但现在他们像Y一样工作。尽量不要认为事情就像X一样，你会让你的生活更轻松。
要在看到此错误时添加到调试工具包中，我建议您查找正在定义或调用的函数，而不要使用左括号'（'。
在您的特定情况下，正如其他答案已经注意到的那样，您的代码缺少'（'at with-open。
(defn makeStructs ;line 27
"open fName as a file and turns each line into a struct.
Returns a Vector of structs"
[fName]
--> with-open[r (reader (file fName))]
你没有打开电话，而是接受它的价值。
我的错误如下：
--> defn ret-col-match
"Returns true false match on sequence position w/ cmp-val."
[row cmp-val col-idx]
(if (= (nth row col-idx nil) cmp-val)
true
false))
你可以看到缺少的'（'在defn之前。