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

This namespace deals with all Cascalog variable transformations.

cascalog-var? clj

(cascalog-var? obj)

A predicate on 'obj' to check is it a cascalog variable.

fully-ground? clj

Returns true if every supplied var is a ground variable, false otherwise.

gen-non-nullable-var clj

Returns a unique non-nullable var with a optional suffix.

gen-non-nullable-vars clj

(gen-non-nullable-vars amt)

Generates the given number, 'amt', of non-nullable variables in a sequence.

Example: (let [var-seq (gen-non-nullable-vars n)] (?<- (hfs-textline out-path) var-seq (in :>> var-seq)))

gen-nullable-var clj

Returns a unique nullable var with a optional suffix.

gen-nullable-vars clj

(gen-nullable-vars amt)

Generates the given number, 'amt', of nullable variables in a sequence.

Example: (let [var-seq (gen-nullable-vars n)] (?<- (hfs-textline out-path) var-seq (in :>> var-seq)))

gen-ungrounding-var clj

Returns a unique ungrounding var with an optional suffix.

gen-var-fn clj

(gen-var-fn prefix)

Accepts a prefix and returns a function of no arguments that, when called, produces a unique string with the supplied prefix.

ground-var? clj

Returns true of the supplied var is capable of triggering a join (prefixed by ! or ?), false otherwise.

logic-prefixes clj

Symbol prefixes reserved by Cascalog for use within predicates. Any symbol or string prefixed by one of these characters will be interpreted as a logic variable.

logic-sym? clj

Returns true if the supplied symbol is a Cascalog logic variable, false otherwise. & and _ are also accepted.

non-nullable-var? clj

(non-nullable-var? sym-or-str)

Returns true if the supplied symbol (or string) references a non-nullable logic variable (prefixed by ?), false otherwise.

nullable-var? clj

Returns true of the supplied symbol (or string) references a nullable logic variable (prefixed by ! or !!)

prefixed-by? clj

(prefixed-by? prefix v)

Returns true if the supplied var v is prefixed by the supplied prefix, false otherwise.

replace-dups clj

(replace-dups coll)

Accepts a sequence returns the set of replacements, plus a new sequence with all duplicates replaced by a call to gen.

reserved? clj

Returns true if the supplied symbol is reserved by Cascalog, false otherwise.

sanitize clj

(sanitize pred)

Accepts a (potentially nested) data structure and returns a transformed, sanitized predicate generated by replacing all wildcards and logic variables with strings.

sanitize-fn clj

(sanitize-fn anon-gen)

Returns a function that sanitizes an element by resolving logic variable names and replacing wildcards using the supplied generator.

selector? clj

Returns true if the supplied keyword is reserved by cascalog, false otherwise.

selectors clj

Keywords that have special meaning within Cascalog's predicates.

unground-var? clj

(unground-var? sym-or-str)

Returns true if the supplied symbol (or string) references an ungrounding logic variable (prefixed by !!), false otherwise.

uniquify-var clj

(uniquify-var v)

Appends a unique suffix to the supplied input.

wildcards clj

Wildcard strings reserved by Cascalog.

with-logic-vars clj macro

(with-logic-vars to-search & body)

Binds all logic variables within the to-search of with-logic-vars to their string equivalents, allowing the user to write bare symbols within the body.

For example:

(with-logic-vars [?a ?b :see] (str ?a ?b :see)) ;=> "?a?b:see"