If the Result is a Ok, passes its value to the predicate. If the predicate returns true, then the Result is returned unchanged. In every other case, an Error gets returned.
forall a: (Maybe a).((a) => Boolean) => Maybe aIf the Result is a Ok, passes its value to the predicate. If the predicate returns true, then the Result is returned unchanged. In every other case, an Error gets returned.
const Result = require('folktale/result');
// This line evaluates to true.
Result.Ok.hasInstance(Result.Ok(3).filter(n => n === 3));
// These lines evaluate to false.
Result.Ok.hasInstance(Result.Ok(2).filter(n => n === 3));
Result.Ok.hasInstance(Result.Error(3).filter(n => n !== 3));
Result.Ok.hasInstance(Result.Error(3).filter(n => n === 3));
{
/*~*/
Error: function filter(predicate) {
assertFunction('Result.Error#filter', predicate);
return this;
},
/*~*/
Ok: function filter(predicate) {
assertFunction('Result.Ok#filter', predicate);
return predicate(this.value) ? this : Error();
}
}