CHANGELOG.md

@@ -6,6 +6,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- `Option.force_msg`
 ### Changed
 ### Removed
 

docs/sophia_stdlib.md

@@ -1293,7 +1293,17 @@ Escapes `option` wrapping by providing default value for `None`.
 Option.force(o : option('a)) : 'a
 ```
 
-Forcefully escapes `option` wrapping assuming it is `Some`. Throws error on `None`.
+Forcefully escapes the `option` wrapping assuming it is `Some`. 
+Aborts on `None`.
+
+
+#### force_msg
+```
+Option.force_msg(o : option('a), err : string) : 'a
+```
+
+Forcefully escapes the `option` wrapping assuming it is `Some`.
+Aborts with `err` error message on `None`.
 
 
 #### contains

priv/stdlib/Option.aes

@@ -26,6 +26,12 @@ namespace Option =
     None    => abort("Forced None value")
     Some(x) => x
 
+/** Assume it is `Some` with custom error message
+ */
+  function force_msg(o : option('a), err : string) : 'a = switch(o)
+    None    => abort(err)
+    Some(x) => x
+
   function contains(e : 'a, o : option('a)) = o == Some(e)
 
   function on_elem(o : option('a), f : 'a => unit) : unit = match((), f, o)