Your first Kotlin file

1. Start with ktFile

ktFile {} is the entry point to Prosa.kt. Use its block to describe the Kotlin source you want to generate. It returns that source as a String.

Use packageName() inside the block to specify the generated file’s package:

import com.alexstyl.prosakt.ktFile

val source = ktFile {
    packageName("com.example.greetings")
}

Generated Kotlin:

package com.example.greetings

This block generates only a package declaration. The resulting string is stored in source; ktFile does not write a file to disk.

2. Add a function that returns a string

Use ktFunction() to declare a function, passing its name as the argument.

Use returns {} to configure the return type. Inside it, use type {} with reference("String") to specify String.

Use body {} to define the function’s body and literal() to generate a literal value. Here, literal("Hello") supplies the string the function returns:

val source = ktFile {
    packageName("com.example.greetings")
    ktFunction("greeting") {
        returns {
            type {
                reference("String")
            }
        }
        body {
            literal("Hello")
        }
    }
}

Generated Kotlin:

package com.example.greetings

fun greeting(): String {
    return "Hello"
}

With an explicit non-Unit return type, Prosa.kt automatically returns the body’s last expression. This function returns "Hello".

3. Add a parameter

Use parameter() inside ktFunction {} to add a parameter to your function, passing its name as the argument. To specify its type, use type {} inside the parameter block, then reference() to name the type:

val source = ktFile {
    packageName("com.example.greetings")
    ktFunction("greeting") {
        parameter("name") {
            type {
                reference("String")
            }
        }
        returns {
            type {
                reference("String")
            }
        }
        body {
            literal("Hello")
        }
    }
}

Generated Kotlin:

package com.example.greetings

fun greeting(name: String): String {
    return "Hello"
}

The function now accepts a name, but still returns "Hello".

4. Use the parameter

Use plus {} inside the literal() block to append an expression to the string. Inside plus {}, use reference("name") to refer to the function’s parameter:

val source = ktFile {
    packageName("com.example.greetings")
    ktFunction("greeting") {
        parameter("name") {
            type {
                reference("String")
            }
        }
        returns {
            type {
                reference("String")
            }
        }
        body {
            literal("Hello, ") {
                plus {
                    reference("name")
                }
            }
        }
    }
}

Generated Kotlin:

package com.example.greetings

fun greeting(name: String): String {
    return "Hello, " + name
}

literal("Hello, ") supplies the greeting text, and reference("name") supplies the parameter reference. plus {} joins them with + in the generated code.