cascalog.logic.predmacro — cascalog/cascalog-core 3.0.0

This namespace contains functions that help to define predicate macro instances, and compile predicate macro instances out into sequences of RawPredicate instances.

build-predmacro clj

(build-predmacro input-decl output-decl raw-predicates)

Build a predicate macro via input and output declarations. This function takes a sequence of declared inputs, a seq of declared outputs and a sequence of raw predicates. Upon use, any variable name not in the input or output declarations will be replaced with a random Cascalog variable (uniqued by appending a suffix, so nullable vs non-nullable will be maintained).

IPredMacro clj protocol

expand clj

(expand _ input output)

Returns a sequence of vectors suitable to feed into cascalog.parse/normalize.

predmacro clj macro

(predmacro & body)

A more general but more verbose way to create predicate macros.

Creates a function that takes in [invars outvars] and returns a list of predicates. When making predicate macros this way, you must create intermediate variables with gen-nullable-var(s). This is because unlike the (<- [?a :> ?b] ...) way of doing pred macros, Cascalog doesn't have a declaration for the inputs/outputs.

See https://github.com/nathanmarz/cascalog/wiki/Predicate-macros

predmacro* clj

(predmacro* fun)

Functional version of predmacro. See predmacro for details.

predmacro? clj

(predmacro? o)

use-as-filter? clj

(use-as-filter? output-decl outvars)

If a predicate macro had a single output variable defined and you try to use it with no output variables, the predicate macro acts as a filter.

validate-declarations! clj

(validate-declarations! input-decl output-decl)

Assert that the same variables aren't used on input and output when defining a predicate macro.