where cheatsheet

Syntax

(where extractor comparator target)
;;=> predicate function

With maps

• (where :field = "value") Use the keyword as a function to extract the value
• (where :age > 18) Comparator can be any clojure function which take two arities.
• (where (comp :zip :address) not= "ABC123") Nested maps can be reached by composing functions.
• (where [:age <= 24]) The condition can be expressed as a vector of 3 elements for better composition.

Logical operators

• (where [:and [:age <= 24] [:country = "USA"]]) :and can be used to connect predicates logically for which all the conditions must be truthy.
• (where [:or [:country = "USA"] [:country = "Italy]]) :or can be used to connect predicates logically for which one the conditions must be truthy.
• (where [:not [:country = "USA"]]) :not can be used to negate the logical value o a single predicate.

Built-in Generic comparators

The generic comparator accept any Clojure value.

• (where :country :is? "Italy") - like =
• (where :country :is-not? "Italy") - like not=
• (where :country :in? ["Italy" "France" "USA"]) - truthy if it matches any of the values listed
• (where :country :not-in? ["Italy" "France" "USA"]) - falsey if it matches any of the values listed

Built-in String comparators

All String comparators they expect a String and are nil safe (don't throw NullPointerException like they String.class counterparts), :matches require a valid Pattern.

• (where :country :starts-with? "Ita") - like String/startsWith
• (where :country :ends-with? "ly") - like String/endsWith
• (where :country :contains? "tal") - like String/indexOf != -1
• (where :country :matches? #"United.*") - like re-find
• (where :country :matches-exactly? #"United.*") - like re-matches
• (where :filename :glob-matches? "*.txt") - like glob pattern or wildcard matching ? for any character, * any number of any characters

Built-in Case-insensitive String comparators

All String comparators they expect a String and are nil safe (don't throw NullPointerException like they String.class counterparts), :MATCHES require a valid Pattern.

• (where :country :IS? "italy") - like String/.equalsIgnoreCase
• (where :country :STARTS-WITH? "ITA") - like String/startsWith, but case insensitive
• (where :country :ENDS-WITH? "ly") - like String/endsWith, but case insensitive
• (where :country :CONTAINS? "tal") - like String/indexOf != -1, but case insensitive
• (where :country :IN? ["ITALY" "france"]) - truthy if it matches any of the values listed, but case insensitive
• (where :country :MATCHES? #"united.*") - like re-find, but case insensitive
• (where :country :MATCHES-EXACTLY? #"united.*") - like re-matches, but case insensitive
• (where :filename :GLOB-MATCHES? "*.txt") - like :glob-matches?, but case insensitive

Built-in Negation of String comparators

All String comparators they expect a String and are nil safe (don't throw NullPointerException like they String.class counterparts), :not-matches and :NOT-MATCHES require a valid Pattern.

• (where :country :not-starts-with? "Ita") - same as (complement (where :country :starts-with? "Ita"))
• (where :country :not-ends-with? "ly") - same as (complement (where :country :ends-with? "ly"))
• (where :country :not-contains? "tal") - same as (complement (where :country :contains? "tal"))
• (where :country :not-matches? #"United.*") - same as (complement (where :country :matches? #"United.*"))
• (where :country :not-matches-exactly? #"United.*") - same as (complement (where :country :matches-exactly? #"United.*"))
• (where :filename :not-glob-matches? "*.txt") - smae as (complement (where :filename :not-glob-matches? "*.txt"))
• (where :country :NOT-STARTS-WITH? "ITA") - same as (complement (where :country :STARTS-WITH? "ITA"))
• (where :country :NOT-ENDS-WITH? "ly") - same as (complement (where :country :ENDS-WITH? "ly"))
• (where :country :NOT-CONTAINS? "tal") - same as (complement (where :country :CONTAINS? "tal"))
• (where :country :NOT-IN? ["ITALY" "france"])- same as (complement (where :country :IN? ["ITALY" "france"]))
• (where :country :NOT-MATCHES? #"united.*") - same as (complement (where :country :MATCHES? #"united.*"))
• (where :country :NOT-MATCHES-EXACTLY? #"united.*") - same as (complement (where :country :MATCHES-EXACTLY? #"united.*"))
• (where :filename :NOT-GLOB-MATCHES? "*.txt") - same as (complement (where :filename :NOT-GLOB-MATCHES? "*.txt"))

Built-in numerical comparators

All numerical comparators are nil safe (don't throw NullPointerException) when one of the argument is nil.

• (where :age :between? [18 34]) - truthy for all number between 18 and 34 (included)
• (where :age :strictly-between? [18 34]) - truthy for all number between 18 and 34 (excluded)
• (where :age :range? [18 34]) - truthy for all number between 18 (inlcuded) and 34 (excluded)
• (where :age :in? [18 22 34 16]) - truthy if the :age is in the given list of values
• (where :age :not-between? [18 34]) - falsey for all number between 18 and 34 (included)
• (where :age :not-strictly-between? [18 34]) - falsey for all number between 18 and 34 (excluded)
• (where :age :not-range? [18 34]) - falsey for all number between 18 (inlcuded) and 34 (excluded)
• (where :age :not-in? [18 22 34 16]) - falsey if the :age is in the given list of values