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by kkukshtel
497 days ago
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Can you say more about how you made a DSL this way? I love C# but one of my (few) issues with it is that its “support” for DSLs is generally subpar compared to the JVM and how Kotlin and Java files can exist side by side in the same project. Would love to know tips about how you approach this! |
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So I should say I'm playing a bit fast and loose with "internal DSL" here, so that might have been a little misleading.
I'm not doing anything fancy like you could do in Scala or Ruby where there are a lot of powerful things you can do to change language syntax.
The main pieces of C# I composed to get what I'm talking are: LINQ/MoreLinq: For my scripting I was almost always automating some kind of a process against collections of things, like performing git actions against a mess of repos, performing an XML transform against a bunch of app.configs, etc.
Extension Methods: Because you can add extensions methods that only appear if the collection you're operating on is a specific _type_ of collection. So I could have an extension method with a signature like this: `public static void Kill(this IEnumerable<Process> processes)` and then I could do this: `Process.GetProcessesByName("node").Kill();` (I didn't test that code, but in principle I know it works). Kind of contrived, because there are a million ways to do that, but it let me create very terse and specific method chains that imo were pretty obvious.
The last thing, that's a lot more finicky and I didn't use as often, but very powerful are ExpressionTrees: https://learn.microsoft.com/en-us/dotnet/csharp/advanced-top...
This is what EF and a lot of other libraries use to generate queries, though you can generate whatever in principle. It's basically a first class mechanism for passing a lambda into a method and instead getting an AST representation of the lambda that you can then do whatever with. E.g., traverse the AST and generate a SQL query or whatever. (apologies if I'm explaining things you already know)
Lmk if I'm missing what you're asking. Like I said, I'm definitely being a little lazy with the DSL moniker, especially compared to something like something you'd make in JetBrains MPS or a DSL workbench, or language where you can more powerfully modify syntax, but above is generally what I meant.