PrettyExpressive.Json

Convert a Doc cost to a compact JSON string.

Each Doc variant is encoded as a JSON object with a "type" field:

• DocFail → {"type":"fail"}
• DocText → {"type":"text","string":"...","width":N}
• DocNewline → {"type":"newline","flatForm":"..."} or {"type":"newline","flatForm":null}
• DocConcat → {"type":"concat","a":{...},"b":{...}}
• DocChoice → {"type":"choice","a":{...},"b":{...}}
• DocNest → {"type":"nest","indent":N,"doc":{...}}
• DocAlign → {"type":"align","doc":{...}}
• DocReset → {"type":"reset","doc":{...}}
• DocAddCost → {"type":"addCost","doc":{...}} (cost value is opaque and omitted)
• DocTwoColumns → {"type":"twoColumns","rows":[{"a":{...},"b":{...}},...] }
• DocBlank → {"type":"blank","width":N} (internal renderer node)
• DocContext → {"type":"context"} (internal renderer node; function not inspectable)
• DocEvaled → {"type":"evaled"} (internal renderer node; measures not inspectable)

String values are JSON-escaped: \ and " are escaped, and the control characters \n, \r, and \t are replaced with their JSON escape sequences.