Constants

constant

function constant( value: T ): Decoder<T> (source)

Accepts only the given constant value.

Try it

constant('hello').verify(input)

null_: Decoder<null> (source)

Accepts and returns only the literal null value. Named null_ because null is a reserved keyword in TypeScript.

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null_.verify(input)

undefined_: Decoder<undefined> (source)

Accepts and returns only the literal undefined value. Named undefined_ because undefined is a reserved keyword in TypeScript.

Try it

undefined_.verify(input)

Input	Result
	undefined
	null ^^^^ Must be undefined
	false ^^^^^ Must be undefined
	"hello world" ^^^^^^^^^^^^^ Must be undefined

function enum_( enum: MyEnum ): Decoder<MyEnum> (source)

Accepts and returns an enum value. Named enum_ because enum is a reserved keyword in TypeScript.

It works with numeric enums:

Try it

enum Fruit {  Apple,  Banana,  Cherry,}enum_(Fruit).verify(input)

As well as with string enums:

Try it

enum Fruit {  Apple = 'a',  Banana = 'b',  Cherry = 'c',}enum_(Fruit).verify(input)