map_insert function

rfc/0005 New Scalable Protocol to power Duniter.md

@@ -527,7 +527,6 @@ grp 2
 > new system functions via soft-forks.
 
 > TODO Token data fetching
-> TODO More operators for arrays and values (byte arrays)
 
 #### Some functions of a "standard library"
 
@@ -547,4 +546,11 @@ sum array = fold array 0 sum_step
 
 > TODO : map_insert allowing to map multiple outputs for 1 input.
 
+##### `map_insert :: (array :: (index) -> (item :: A)) -> (fun :: (item :: A) -> (array :: (index) -> (value :: B))) -> (array :: (index) -> (item :: B))`
+
+```txt
+-- each iteration can return an array of 0, 1 or more values which are merged together.
+map_insert array fun = merge (map array fun)
+```
+
 #### Execution