I write a file named "baby.hs" with the following codes
我用以下代码写了一个名为“baby.hs”的文件
bmiTell :: => Double -> String
bmiTell bmi
| bmi <= 1 = "small"
| bmi <= 10 = "medium"
| bmi <= 100 = "large"
| otherwise = "huge"
When I load this file in GHCi, it complains like this:
当我在GHCi中加载这个文件时,它抱怨如下:
ghci>:l baby.hs
[1 of 1] Compiling Main ( baby.hs, interpreted )
baby.hs:1:12: parse error on input ‘=>’
Failed, modules loaded: none.
ghci>
If I remove the =>, it doesn't work either:
如果我删除=>,它也不起作用:
bmiTell :: Double -> String
bmiTell bmi
| bmi <= 1 = "small"
| bmi <= 10 = "medium"
| bmi <= 100 = "large"
| otherwise "huge"
Error info:
ghci>:l baby
[1 of 1] Compiling Main ( baby.hs, interpreted )
baby.hs:7:1:
parse error (possibly incorrect indentation or mismatched brackets)
Failed, modules loaded: none.
Does anyone have ideas about this?
有没有人有这个想法?
1 个解决方案
#1
In your first case, your type signature is wrong. It should be like this:
在您的第一种情况下,您的类型签名是错误的。它应该是这样的:
bmiTell :: Double -> String -- Notice that there is no =>
In your second case, you are missing = in the last line. It should be like this:
在你的第二种情况下,你在最后一行中缺少了=。它应该是这样的:
| otherwise = "huge" -- Notice the presence of =
So a proper working code will look like this:
所以正确的工作代码将如下所示:
bmiTell :: Double -> String
bmiTell bmi
| bmi <= 1 = "small"
| bmi <= 10 = "medium"
| bmi <= 100 = "large"
| otherwise = "huge"
#1
In your first case, your type signature is wrong. It should be like this:
在您的第一种情况下,您的类型签名是错误的。它应该是这样的:
bmiTell :: Double -> String -- Notice that there is no =>
In your second case, you are missing = in the last line. It should be like this:
在你的第二种情况下,你在最后一行中缺少了=。它应该是这样的:
| otherwise = "huge" -- Notice the presence of =
So a proper working code will look like this:
所以正确的工作代码将如下所示:
bmiTell :: Double -> String
bmiTell bmi
| bmi <= 1 = "small"
| bmi <= 10 = "medium"
| bmi <= 100 = "large"
| otherwise = "huge"