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Schema to Pretty Printer

The Pretty.make function is used to create pretty printers that generate a formatted string representation of values based on a schema.

Example (Pretty Printer for a Struct Schema)

import { Pretty, Schema } from "effect"


const Person = Schema.Struct({
  name: Schema.String,
  age: Schema.Number,
})


// Create a pretty printer for the schema
const PersonPretty = Pretty.make(Person)


// Format and print a Person object
console.log(PersonPretty({ name: "Alice", age: 30 }))
/*
Output:
'{ "name": "Alice", "age": 30 }'
*/

Customizing Pretty Printer Generation

You can customize how the pretty printer formats output by using the pretty annotation within your schema definition.

The pretty annotation takes any type parameters provided (typeParameters) and formats the value into a string.

Example (Custom Pretty Printer for Numbers)

import { Pretty, Schema } from "effect"


// Define a schema with a custom pretty annotation
const schema = Schema.Number.annotations({
  pretty: (/**typeParameters**/) => (value) => `my format: ${value}`,
})


// Create the pretty printer
const customPrettyPrinter = Pretty.make(schema)


// Format and print a value
console.log(customPrettyPrinter(1))
// Output: "my format: 1"