spec-coerce 
A Clojure(script) library designed to leverage your specs to coerce your information into correct types.
Spec Coerce will remain in alpha while clojure.spec still in alpha.
Usage
Learn by example:
(ns spec-coerce.example
(:require
[clojure.spec.alpha :as s]
[spec-coerce.core :as sc]))
; Define a spec as usual
(s/def ::number int?)
; Call the coerce method passing the spec and the value to be coerced
(sc/coerce ::number "42") ; => 42
; Like spec generators, when using `and` it will use the first item as the inference source
(s/def ::odd-number (s/and int? odd?))
(sc/coerce ::odd-number "5") ; => 5
; When inferring the coercion, it tries to resolve the upmost spec in the definition
(s/def ::extended (s/and ::odd-number #(> % 10)))
(sc/coerce ::extended "11") ; => 11
; Nilables are considered
(s/def ::nilable (s/nilable ::number))
(sc/coerce ::nilable "42") ; => 42
(sc/coerce ::nilable "nil") ; => nil
(sc/coerce ::nilable "foo") ; => "foo"
; The coercion can even be automatically inferred from specs given explicitly as sets of a homogeneous type
(s/def ::enum #{:a :b :c})
(sc/coerce ::enum ":a") ; => :a
; If you wanna play around or use a specific coercion, you can pass the predicate symbol directly
(sc/coerce `int? "40") ; => 40
; Parsers are written to be safe to call, when unable to coerce they will return the original value
(sc/coerce `int? "40.2") ; => "40.2"
(sc/coerce `inst? "date") ; => "date"
; To leverage map keys and coerce a composed structure, use coerce-structure
(sc/coerce-structure {::number "42"
::not-defined "bla"
:sub {::odd-number "45"}})
; => {::number 42
; ::not-defined "bla"
; :sub {::odd-number 45}}
; coerce-structure supports overrides, so you can set a custom coercer for a specific context, and can be also a point
; to set coercer for unqualified keys
(sc/coerce-structure {::number "42"
::not-defined "bla"
:unqualified "12"
:sub {::odd-number "45"}}
{::sc/overrides {::not-defined `keyword?
:unqualified ::number}})
; => {::number 42
; ::not-defined :bla
; :unqualified 12
; :sub {::odd-number 45}}
; If you want to set a custom coercer for a given spec, use the spec-coerce registry
(defrecord SomeClass [x])
(s/def ::my-custom-attr #(instance? SomeClass %))
(sc/def ::my-custom-attr #(map->SomeClass {:x %}))
; Custom registered keywords always takes precedence over inference
(sc/coerce ::my-custom-attr "Z") ; => #user.SomeClass{:x "Z"}
; Coercers in the registry can be overriden within a specific context
(binding [sc/*overrides* {::my-custom-attr keyword}]
(sc/coerce ::my-custom-attr "Z")) ; => :ZExamples from predicate to coerced value:
; Numbers
(sc/coerce `number? "42") ; => 42.0
(sc/coerce `integer? "42") ; => 42
(sc/coerce `int? "42") ; => 42
(sc/coerce `pos-int? "42") ; => 42
(sc/coerce `neg-int? "-42") ; => -42
(sc/coerce `nat-int? "10") ; => 10
(sc/coerce `even? "10") ; => 10
(sc/coerce `odd? "9") ; => 9
(sc/coerce `float? "42.42") ; => 42.42
(sc/coerce `double? "42.42") ; => 42.42
(sc/coerce `zero? "0") ; => 0
; Numbers on CLJS
(sc/coerce `int? "NaN") ; => js/NaN
(sc/coerce `double? "NaN") ; => js/NaN
; Booleans
(sc/coerce `boolean? "true") ; => true
(sc/coerce `boolean? "false") ; => false
(sc/coerce `true? "true") ; => true
(sc/coerce `false? "false") ; => false
; Idents
(sc/coerce `ident? ":foo/bar") ; => :foo/bar
(sc/coerce `ident? "foo/bar") ; => 'foo/bar
(sc/coerce `simple-ident? ":foo") ; => :foo
(sc/coerce `qualified-ident? ":foo/baz") ; => :foo/baz
(sc/coerce `keyword? "keyword") ; => :keyword
(sc/coerce `keyword? ":keyword") ; => :keyword
(sc/coerce `simple-keyword? ":simple-keyword") ; => :simple-keyword
(sc/coerce `qualified-keyword? ":qualified/keyword") ; => :qualified/keyword
(sc/coerce `symbol? "sym") ; => 'sym
(sc/coerce `simple-symbol? "simple-sym") ; => 'simple-sym
(sc/coerce `qualified-symbol? "qualified/sym") ; => 'qualified/sym
; Collections
(sc/coerce `(s/coll-of int?) ["5" "11" "42"]) ; => [5 11 42]
(sc/coerce `(s/coll-of int?) ["5" "11.3" "42"]) ; => [5 "11.3" 42]
(sc/coerce `(s/map-of keyword? int?) {"foo" "42" "bar" "31"})
; => {:foo 42 :bar 31}
; Branching
; tests are realized in order
(sc/coerce `(s/or :int int? :bool boolean?) "40") ; 40
(sc/coerce `(s/or :int int? :bool boolean?) "true") ; true
; returns original value when no options can handle
(sc/coerce `(s/or :int int? :bool boolean?) "nil") ; "nil"
; Tuple
(sc/coerce `(s/tuple int? string?) ["0" 1]) ; => [0 "1"]
; Others
(sc/coerce `uuid? "d6e73cc5-95bc-496a-951c-87f11af0d839") ; => #uuid "d6e73cc5-95bc-496a-951c-87f11af0d839"
(sc/coerce `inst? "2017-07-21") ; => #inst "2017-07-21T00:00:00.000000000-00:00"
(sc/coerce `nil? "nil") ; => nil
(sc/coerce `nil? "null") ; => nil
;; Clojure only:
(sc/coerce `uri? "http://site.com") ; => (URI. "http://site.com")
(sc/coerce `decimal? "42.42") ; => 42.42M
(sc/coerce `decimal? "42.42M") ; => 42.42M
;; Throw exception when coercion fails
(sc/coerce! `int? "abc") ; => throws (ex-info "Failed to coerce value" {:spec `int? :value "abc"})
(sc/coerce! :simple-keyword "abc") ; => "abc", coerce! doesn't do anything on simple keywords
;; Conform the result after coerce
(sc/conform `(s/or :int int? :bool boolean?) "40") ; [:int 40]
;; Throw on coerce structure
(sc/coerce-structure {::number "42"} {::sc/op sc/coerce!})
;; Conform on coerce structure
(sc/coerce-structure {::number "42"} {::sc/op sc/conform})License
Copyright Β© 2017 Wilker LΓΊcio
Distributed under the MIT License.