This library tries to provide a way to detect what kind of type the given predicate is trying to check. This is different from inferring the return type of a function. For example,
(eq 'null (test-type '(eql nil ?)))
(eq 'string (test-type '(stringp ?)))
The inference is done on form basis, and the equivalence of predicates are
determined by #'equal. To simplify the design, the argument to check
should be a symbol ?, exported in package type-i.
Function test-type returns the inferred type. In contrast, type-tests
returns a list of all possible test predicates that returns true when ?
is bound to the object of interest.
(is (subset '((TYPEP ? 'integer)
(integerp ?))
(type-tests 'integer)))
;; more inference on integers, e.g., (< 0 ? 4), should be added
(is (subset '((TYPEP ? '(mod 5))
(TYPEP ? '(integer 0 4)))
(type-tests '(mod 5))))
This library is extensible. with define-inference-rule macro, you can add
more inferers to improve this library. Each inference rule is a unary
function that takes a predicate form, then returns a list of more
forms.
The test-type searches in the form space, adding the results of each
inference rule, until a form (typep ? X) is found (where X is
unknown). If it fails to find such a form even if the maximal set
is obtained, then the test-type returns nil. type-tests just returns
the maximal set.
I currently implemented the following inference rules:
- typep –
(typep ? 'array)->(arrayp ?)etc. - unary –
(arrayp ?)->(typep ? 'array) (typep ? '(array)) (typep ? '(array *))… - null –
(null ?) (typep ? null) (eql ? nil) (eql nil ?) (eq ? nil)… - derived – call
typexpand
Inference on exhaustive partitions, e.g., (typep ? 'list) -> (typep ?
'(or cons null)) is planned.
This library is at least tested on implementation listed below:
- SBCL 1.2.8 on X86-64 Linux 3.13.0-46-generic (author’s environment)
Also, it depends on the following libraries:
- Trivia by Masataro Asai
- NON-Optimized Pattern Matching Library
- alexandria by
- Alexandria is a collection of portable public domain utilities.
- iterate by
- Jonathan Amsterdam’s iterator/gatherer/accumulator facility
- introspect-environment by Bike <aeshtaer@gmail.com>
- Small interface to portable but nonstandard introspection of CL environments.
- Masataro Asai (guicho2.71828@gmail.com)
Copyright (c) 2015 Masataro Asai (guicho2.71828@gmail.com)
Licensed under the LLGPL License.