•mime — Rich display

•mime Y returns the MIME bundle that display uses for Y. The bundle is a keyed vector from MIME types to text, or to bytes for a binary type such as image/png. It always has text/plain. If Y has a renderer, •mime calls it with Y as ⍵ and adds its entries.

The built-in renderers add these types:

• text/html: element functions. Natively, a •canvas drawing too, as HTML that holds its data and the script that draws it.
• image/svg+xml: •svg and •plot.
• image/png: •image. An animation is an animated PNG in both builds.
• image/x-rgba;width=N: a still •image picture in the browser build, as RGBA pixels, N pixels wide. In JavaScript, new ImageData(new Uint8ClampedArray(bytes.buffer), N) makes a canvas image from the bytes.
• application/x-bpl-canvas+json and application/x-bpl-canvas-data: a •canvas drawing in the browser build. The npm package’s canvas.js is a script whose value is a function that draws it: (0, eval)(script)(canvas, json, bytes), where canvas is a <canvas> element and json and bytes are the two entries.

F •mime Y returns Y with the renderer that F holds, as in {["text/html":"</b>",⍨"<b>",⍕⍵]}ᵘ •mime Y. A MIME type on the left displays Y itself as that type, as in "text/markdown" •mime "*hi*". An atom becomes a scalar, because only an array can hold a renderer.

A result keeps a renderer when it has an item for each item of its argument, as pervasive functions, Each and scans do. Rearranging or selecting from an array without removing an axis also keeps it, as reversal, transpose, take, replicate and catenation do. Changes in place keep it. Other functions drop it, as reductions and ⍴ do. When two arguments have different renderers, the result has none. Match ignores renderers.

Display shows the text form when a renderer fails. Only a direct •mime call reports the error. Rich display covers renderers.

Errors: DOMAIN for a left argument that holds neither a function nor text.