9.10 Functors

The module Functor contains procedures operating on functors.

is

{Functor.is +X ?B}

tests whether X is a functor.

new

{Functor.new <import spec> <export spec> +P ?Functor}

returns a new functor with imports as described by the <import spec>, exports as described by the <export spec>, and body as performed by P.

The <import spec> is a record mapping the name of each imported module to a record giving information about it:

<import spec> ::=
		'import'(<module name>: <import info> ...
		<module name>: <import info>)

<module name>

::=

<atom>

The optional 'from' field gives the value of this import's at clause, if given:

<import info>

::=

info(type: <type> ['from': <atom>])

The type field is the expected type of the module. This can be any of the atoms returned by Value.type, plus some more implementation-specific ones, or a record with label record:

<type> ::=
		int | atom | ...	% see above
	|	record(<feature>: <type> ... <feature>: <type>)
	|	nil	% no information known

The <export spec> is a record mapping each feature of the module resulting from applications of this functor to the type of the corresponding value:

<export spec>

::=

'export'(<feature>: <type> ... <feature>: <type>)

The body is a binary procedure {P <import> <export>} where:

<import>

::=

'IMPORT'(<module name>: <value> ... <module name>: <value>)

<export>

::=

<value>