Do you think it is feasible to write a GLSL DSL wi...

# dsl

[rad]

Do you think it is feasible to write a GLSL DSL within Kotlin? I feel like an annoying thing would be having keywords and statements like if as they're already used by the language, so you'd need

`if` (variableA eq variableB)

which feels slightly annoying to use. Is there any alternatives (compiler plugin?) or would it just not be possible?

Example of what I'm talking about:

buildGlslShader { // this: GlslShaderContext
    glPosition = projMat * modelViewMat * vec4(position, 1.0)
    val iColor = ivec3(color.xyz * 255 + vec3(0.5))

    `if` (iColor eq ivec3(78, 92, 36) {
        // Change some stuff...
     }
}

[efemoney]

Are you facing any issues with language injection (in strings)?

[rad]

Sorry for the late response @efemoney but I don't quite understand your question. What's language injection?

[efemoney]

No problem. You can annotate a string literal with a specific language and IJ will provide syntax highlighting & IntelliSense for the string, example

[rad]

Oh, that's pretty cool! Unfortunate the tooling for any kind of GLSL-related things is horrible, especially in IJ.

[efemoney]

Latest Android Studio should support language injection for AGSL strings. But not sure about vanilla IJ support

[efemoney]

Ah I see, tough.

[Matteo Mirk]

To understand, why can't you use a Kotlin if to conditionally execute DSL expressions? Why do you need an alternative ``if`` ?

[rad]

I'm making a DSL for GLSL code generation, probably should've specified that, sorry

[Matteo Mirk]

no worries, thanks for clarifying. So in your case you would like an expression in your DSL to generate an if for GLSL, correct? If backticks bother you, how about this:
have a sealed type for GLSL directives

sealed class GlslDirective {
    data object If : GlslDirective() {
        operator fun invoke(value: String, setup: () -> Unit) {
            TODO("Not yet implemented")
        }
    }
    // more stuff if you want to extend the DSL...
}

then you can use it like:

buildGlslShader {
    If("I don't know what eq produces") {
        // Change some stuff...
    }
}

would this be useful to you?

[Matteo Mirk]

I used a sealed hierarchy because you may want some stuff in common to be available to directives

[Matteo Mirk]

ah yea sorry, the above needs to be hammered onto GlslShaderContext, forgot it 🤦‍♂️

[Matteo Mirk]

I overlooked that, so maybe in your case it would just be a matter of naming the function "If"...

fun GlslShaderContext.If(value: String, setup: GlslShaderContext.() -> Unit) {
    // Do something with value
    setup()
}

sorry, I've complicated things unnecessarily, I'm not sure what I had in mind... 😄

[rad]

Oh that's a good idea! Will definitely try that!

[Matteo Mirk]

YW, let me know if it turns out good