Add guest post. #90
Add guest post. #90
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| title: "Create a simple macro" | |||
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Perhaps "Creating a simple macro" would be better
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| ```nim | ||
| template adder(graph, src, dest): untyped = | ||
| graph.addEdge(initEdge(initNode(src), initNode(dest))) |
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be consistent with your indentation, this has 3 spaces :)
| this: `` `->`(result, "Boston", "Providence") ``. A macro, however can be used | ||
| to create a simpler and more appealling syntax. | ||
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| > Macros can be used to implement domain specific languages. |
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This will look a bit odd as a blockquote. Might be better to recreate the admonition HTML generated in this post: https://nim-lang.org/blog/2017/10/02/documenting-profiling-and-debugging-nim-code.html
(It uses adoc for this, but you should be able to just write that HTML into the document)
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This is hard for me. Can you provide the html?
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| ```nim | ||
| proc buildCityGraph(): Digraph = | ||
| result = initGraph() |
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Wouldn't it be better to generate this in the macro?
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You mean the init function? Well I thought (also sections like edges: ...) so but I just wanted something really simple.
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| What is important to understand now is that, while we are done, procedurally | ||
| modifying an AST is not the correct solution. It is a tree after all. Also it |
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Huh? This doesn't explain why that is not a correct solution at all. It looks perfectly correct to me.
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Hopping someone can provide better reasoning here but i stand by this opinion.
| From making this simple macro we can take away how to structure procs that | ||
| transform the Nim AST. | ||
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| > **Bonus excersise** In the ``buildCityGraph`` proc we see there is an undirected edge. |
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I would write this like so:
"There is an undirected edge in the buildCityGraph proc. Can you ..."
It reads better because it's more concise.
| Hello, as you might know Nim is a powerful programming language that supports | ||
| metaprogramming using macros. Though a lot of Nim programmers are unaware about | ||
| the merits of them due to lack of learning resources. In the first part of | ||
| this series we will discuss the use of macros to simplify the creation of |
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I would recommend going through and removing any use of "we" in sentences. This sentence can be rewritten to:
"The first part of this series will discuss the ..."
It makes sentences more concise and thus easier to read.
| if n.kind == nnkInfix and $n[0] == "->": | ||
| # we pass the template to getAst to avoid constructing | ||
| # the AST manualy | ||
| result.add getAst(adder(head, n[1], n[2])) |
| # a parent node is created with the correct kind. | ||
| result = copyNimNode(body) | ||
| for n in body: | ||
| result.add graphDslImpl(head, n) |
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I don't see why this code is better than the version above.
| title: "Create a simple macro" | ||
| author: Antonis Geralis | ||
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Please add a "Guest Post" div, like done here:
https://nim-lang.org/blog/2018/01/22/yes-command-in-nim.html
Look in the underlying .md to see how it's done.
| the possibility of using an operator with a nice syntax. Although operators can | ||
| have more than two parameters, we are limited into calling them like | ||
| this: `` `->`(result, "Boston", "Providence") ``. A macro, however can be used | ||
| to create a simpler and more appealling syntax. |
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Actually a template would work for this too. I understand that you want to show off macros here, so add maybe "(A template could do so too here, but I want to show how macros work.)"
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Just curious, you mean, result is hardcoded in the template?
| result.add getAst(adder(head, n[1], n[2])) | ||
| ``` | ||
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| What is important to understand now is that, while we are done, procedurally |
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Change this paragraph to "This macro is incomplete however, it doesn't replace nested usages of ->. We would like to replace -> anywhere in the passed body, so let's use recursion with the help of a helper called graphDslImpl .
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@dom96 done. |
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