Create a type

A type is a closure that validates a value and an attached spec describing it. Calling the type validates and returns the value; everything else in rdantic is built by composing types.

Usage

new_type(name, validate, schema = function() list(), ...)

Arguments

name

The type's name, used in error messages and in print().

validate

function(x, path) returning the (possibly coerced) value, or the result of .bad()/.fail().

schema

function() returning the JSON Schema fragment for the type.

...

Extra entries stored in the spec, such as scalar, empty, default, elt or members.

Value

An object of class type.

Examples

even <- new_type(
  "even",
  validate = function(x, path) {
    if (is.numeric(x) && all(x %% 2 == 0)) x else rdantic:::.bad(path, "even", type_of(x))
  },
  schema = function() list(type = "integer", multipleOf = 2)
)
even(c(2, 4))
#> [1] 2 4
try(even(3))
#> Error : 1 validation problem in even
#>   <value>  expected even, got num[1]
schema(even)
#> $type
#> [1] "integer"
#> 
#> $multipleOf
#> [1] 2
#>