Idiom # 231: Test if bytes are a valid UTF-8 string

See programming-idioms.org:

Code

b := strings.fromBytes(s).codepointsAndErrors ∀ fun (x outcome<codepoint>) => x.ok

Running Example

ex231 is bytesOk := [1.as_u8, 2.as_u8, 3.as_u8, 4.as_u8, 5.as_u8] bytesNotOk := [200.as_u8, 1.as_u8, 201.as_u8, 2.as_u8, 203.as_u8] s := bytesOk b := strings.fromBytes(s).codepointsAndErrors ∀ fun (x outcome<codepoint>) => x.ok say "utf8? $s: $b" s := bytesNotOk b := strings.fromBytes(s).codepointsAndErrors ∀ fun (x outcome<codepoint>) => x.ok say "utf8? $s: $b"