Error Recovery

Source

github.com/denful/bend

alt lensA lensB

Try lensA; fall back to lensB on left.

(bend.alt bend.str bend.int).get 42     # right 42
(bend.alt bend.str bend.int).get true   # left true

choice [lens ...]

Try each lens in order; return first right or final left.

recover f lens

Call f left-value to attempt recovery; f must return Either.

let port = bend.recover
  (v: if builtins.isString v
      then let n = builtins.fromJSON v;
           in if builtins.isInt n then bend.right n else bend.left v
      else bend.left v)
  bend.int;
in port.get "8080"   # right 8080