2.6 The COMMON-EXTENSIONS module
false-or
Function
Summary
Returns a union type comprised of singleton(#f) and one or more types.
Signature
false-or type #rest more-types => result-type
Arguments
- type
- An instance of
<type>. - more-types
- Instances of
<type>.
Values
- result-type
- An instance of
<type>.
Library
common-extensions
Module
common-extensions
Description
Returns a union type comprised of singleton(#f), type, any other types passed as more-types.
This function is useful for specifying slot types and function return values.
The expression
false-or(t1, t2, ..)
is type-equivalent to
type-union(singleton(#f), t1, t2, ..)