Haskell错误 - 顶级裸体表达 [英] Haskell Error - Naked Expression at Top Level

问题描述

我有以下代码：

I have the following code:

fib n
    | n == 0  = 0
    | n == 1  = 1
    | n > 1  = fib (n-1) + fib (n-2)

print fib 5

由于某种原因，它抛出了一个错误：

And for some reason, it's throwing an error:

[1 of 1] Compiling Main             ( test.hs, test.o )

test.hs:8:1: Parse error: naked expression at top level

发生了什么事？

推荐答案

顶层不能有表达式。 Haskell程序入口点是 Main 模块中的 main 函数。还有 print fib 5 调用 print 有两个参数，您需要这样做：

You cannot have an expression at the top-level. Haskell program entry point is a main function in Main module. Also print fib 5 calls print with two arguments, you need to do:

main = print $ fib 5

或

main = print (fib 5)

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