Shell: add assoc combinator to Data_encoding.

src/proto/environment/data_encoding.mli

@@ -147,6 +147,8 @@ val merge_tups : 'a1 encoding -> 'a2 encoding -> ('a1 * 'a2) encoding
 val array : 'a encoding -> 'a array encoding
 val list : 'a encoding -> 'a list encoding
 
+val assoc : 'a encoding -> (string * 'a) list encoding
+
 type 't case
 val case :
   ?tag:int -> 'a encoding -> ('t -> 'a option) -> ('a -> 't) -> 't case

src/utils/data_encoding.ml

@@ -719,6 +719,10 @@ module Encoding = struct
         `Variable in
     make @@ Mu (kind, name, self)
 
+  let assoc enc =
+    let json = Json_encoding.assoc (Json.get_json enc) in
+    let binary = list (tup2 string enc) in
+    raw_splitted ~json ~binary
 end
 
 include Encoding

src/utils/data_encoding.mli

@@ -155,6 +155,8 @@ val merge_tups : 'a1 encoding -> 'a2 encoding -> ('a1 * 'a2) encoding
 val array : 'a encoding -> 'a array encoding
 val list : 'a encoding -> 'a list encoding
 
+val assoc : 'a encoding -> (string * 'a) list encoding
+
 type 't case
 val case :
   ?tag:int -> 'a encoding -> ('t -> 'a option) -> ('a -> 't) -> 't case