Haskell——显示函数更容易阅读？（用于调试）

发布于 2024-11-26 02:05:02 字数 1452 浏览 2 评论 0原文

我正在寻找像 show 这样的函数，它可以产生更具可读性的输出。它当然不必适用于所有课程。我在谷歌上搜索了“haskell Pretty print”，但这似乎会产生编译器源代码打印机。调试如下内容（手动插入换行符以进行 stackoverflow 格式化）非常困难！

(fromList [(Ref {name = "phi", lenRef = 4},fromList [CompNode {val = 1, ident = CNId {uid =     4,
 zone = 0}, deps = []},CompNode {val = 2, ident = CNId {uid = 5, zone = 0}, deps = []},CompNode 
{val = 3, ident = CNId {uid = 6, zone = 0}, deps = []},CompNode {val = 4, ident = CNId {uid = 7, 
zone = 0}, deps = []}] :: Data.Vector.Vector),(Ref {name = "phi'", lenRef = 2},fromList [CompNode 
{val = -1, ident = CNId {uid = 0, zone = 0}, deps = []},CompNode {val = -1, ident = CNId {uid = 1, 
zone = 0}, deps = []}] :: Data.Vector.Vector),(Ref {name = "psi", lenRef = 2},fromList [CompNode 
{val = -1, ident = CNId {uid = 8, zone = 0}, deps = [CompNode {val = 1, ident = CNId {uid = 4, zone
 = 0}, deps = []},CompNode {val = 2, ident = CNId {uid = 5, zone = 0}, deps = []}]},CompNode {val = 
-1, ident = CNId {uid = 3, zone = 0}, deps = []}] :: Data.Vector.Vector)]

编辑

好吧，我忘记了“print”在haskell中更准确地称为“show”...有一个“pretty-show”包。然而，它似乎只是调用 show，解析字符串，并尝试以良好的方式输出它。我真的想要一些公开新类结构的东西，例如 class PrettyShow a where PrettyShow :: a ->字符串。

edit 2

pretty-show 对于我的情况来说不够好；它的输出几乎没有什么不同。我正在写一些带有跟踪缩进的 monad 的东西；如果代码演变成足够好的东西，也许我会将其发布在 hackage 上。此外，我想为我的自定义类编写 PrettyShow 实例，就像当前可以编写 show 实例一样。

原文

I'm looking for a function like show that produces more readable output. It certainly doesn't have to work on all classes. I searched "haskell pretty print" on Google, but that seems to produce compiler source code printers. Debugging stuff like the following (newlines inserted manually for stackoverflow formatting) is difficult!

(fromList [(Ref {name = "phi", lenRef = 4},fromList [CompNode {val = 1, ident = CNId {uid =     4,
 zone = 0}, deps = []},CompNode {val = 2, ident = CNId {uid = 5, zone = 0}, deps = []},CompNode 
{val = 3, ident = CNId {uid = 6, zone = 0}, deps = []},CompNode {val = 4, ident = CNId {uid = 7, 
zone = 0}, deps = []}] :: Data.Vector.Vector),(Ref {name = "phi'", lenRef = 2},fromList [CompNode 
{val = -1, ident = CNId {uid = 0, zone = 0}, deps = []},CompNode {val = -1, ident = CNId {uid = 1, 
zone = 0}, deps = []}] :: Data.Vector.Vector),(Ref {name = "psi", lenRef = 2},fromList [CompNode 
{val = -1, ident = CNId {uid = 8, zone = 0}, deps = [CompNode {val = 1, ident = CNId {uid = 4, zone
 = 0}, deps = []},CompNode {val = 2, ident = CNId {uid = 5, zone = 0}, deps = []}]},CompNode {val = 
-1, ident = CNId {uid = 3, zone = 0}, deps = []}] :: Data.Vector.Vector)]

edit

okay, I forgot "print" is more accurately called "show" in haskell... there is a "pretty-show" package. however, it seems to just call show, parse the string, and try to output it in a nice way. i really want something that exposes a new class structure, e.g. class PrettyShow a where prettyShow :: a -> String.

edit 2

pretty-show isn't good enough for my situation; its output is hardly different. I'm writing something with a monad that tracks indentation; if the code evolves into something good enough maybe I'll post it on hackage. Further, I want to write PrettyShow instances for my custom classes just like one can currently write show instances.

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余生共白头 2024-12-03 02:05:02

show 函数并不是真正旨在产生可读性良好的输出。如果您查看 deriving 子句和语言规范如何谈论它，很明显 show 和 read 旨在充当简单序列化的一种形式。此外，序列化格式预计可以解析为 Haskell 源，这样（假设相关定义在范围内）将 show 的输出解释为表达式，给出的值相当于使用read对其进行反序列化。

如果你想要漂亮的、格式化的输出，看起来不像 Haskell 源代码，那么标准术语仍然是“漂亮的打印”，并且没有标准的通用方法可以做到这一点。有一些漂亮的打印库提供了构建您自己的漂亮打印机的原语，但是，如果您稍微浏览一下 Hackage。请注意，即使他们谈论编译器中的漂亮打印语法树，这也只是一个示例；任何树状结构都应该同样有效。

作为一种快速替代方案，您可能希望 show 的输出至少是看起来更好的准源代码。这是合理且可能的，因为 read 足够聪明，可以忽略空格等。 groom 包提供了此功能，以“做最愚蠢的事情”这可能会工作”的方式：它将 show 的输出解析为 Haskell 源，然后漂亮地打印它。实际上，这非常有效。