Muotti

Noun.

1. mould/mold (hollow form or matrix for shaping a fluid or plastic substance)
2. cast (mould used to make cast objects)
3. die
4. form (thing that gives shape to other things as in a mold)

^{(source: https://en.wiktionary.org/wiki/muotti)}

Muotti is a graph based value transformer library which aims to solve value transformation by utilizing a digraph of known transformations to produce a transformer chain which is then used to perform the actual transformation.

Usage

Given a map of adjacencies - that is, edges of a graph - with validation and transformer functions:

(require '[muotti.core :as muotti])

(def config {:transformations {[:keyword :string] {:validator   keyword?
                                                   :transformer name}
                               [:string :number]  {:validator   string?
                                                   :transformer parse-long}
                               [:string :boolean] {:validator   string?
                                                   :transformer boolean}
                               [:number :string]  {:validator    number?
                                                   :transformer str}}})

a transformer can be created:

(def t (muotti/->transformer transformations))

which is then immediately usable for transforming values:

(muotti/transform t :keyword :number :123)
; => 123
(muotti/transform t :number :keyword 123)
; => :123

Unresolvable transformations return a special value:

(muotti/transform t :keyword :double :3.14)
; => ::unknown-path

Transformer chain validation errors also return a special value:

(def broken-adjacency {[:a :b] {:validator   keyword?
                                :transformer str})
(def t2 (->transformer broken-adjacency))
(muotti/transform t2 :a :b "not a number")
; => ::invalid-value