Macromania OutFS

Macros for Macromania to describe output directory structures via nested macros:

<Dir name="recipes">
  <File name="index.md">These are good recipes.</File>
  <Dir name="dessert">
    <File name="chocolate_cake.md">Mix chocolate and cake, serve in bowl.</File>
    <File name="icecream.md">Put cream into freezer, then eat quickly.</File>
  </Dir>
</Dir>;

Creates a directory hierarchy (in the real file system, rooted at the current working directory of the process):

- recipes
    - index.md
    - dessert
        - chocolate_cake.md
        - icecream.md

The macros internally track a “current out directory” in the directory hierarchy. Use the outCwd and outFilename functions to access the current position from other macros.

<Dir name="foo">
  {/* evaluates to `/foo;null`*/}
  <impure fun={(ctx) => {
    return `${renderOutFsPath(outCwd(ctx))};${outFilename(ctx)}`;
  }} />
  <Dir name="bar">
    <File name="baz.txt">
      {/* evaluates to `/foo/bar;baz.txt`*/}
      <impure fun={(ctx) => {
        return `${renderOutFsPath(outCwd(ctx))};${outFilename(ctx)}`;
      }} />
    </File>
  </Dir>
</Dir>

You can change the current out directory with the Cd macro, to create directories and files outside the current position (intended less for writing by hand but more as an implementation detail of other macros):

<Dir name="recipes">
  <Dir name="dessert">
    {/* without the `create` flag it would not create the dir but error*/}
    <Cd path={absoluteOutFsPath(["recipes", "breakfast"])} create>
      <File name="breadrolls.md">
        Buy bread, roll on the floor for 48 hours.
      </File>
    </Cd>
    {/* The number gives the number of ".." at the start of the path.*/}
    <Cd path={relativeOutFsPath(["breakfast"], 1)}>
      <File name="cereals.md">
        If you need a recipe, you are doing it wrong.
      </File>
    </Cd>
    <File name="icecream.md">Put cream into freezer, then eat quickly.</File>
  </Dir>
</Dir>;

Produces:

- recipes
    - dessert
      - icecream.md
    - breakfast
        - breadrolls.md
        - cereals.md

The Dir and File macros take an optional mode prop to guide what happens if a file already exists: "timid" is the default mode, it halts evaluation with an error. "placid" leaves any preexisting file of the same name untouched. "assertive" overwrites any preexisting file of the same name.