☰
bind
outcome.bind
Functions
create a String from this instance. Unless redefined, `a.as_string` will
create `"instance[T]"` where `T` is the dynamic type of `a`
create `"instance[T]"` where `T` is the dynamic type of `a`
Get the dynamic type of this instance. For value instances `x`, this is
equal to `type_of x`, but for `x` with a `ref` type `x.dynamic_type` gives
the actual runtime type, while `type_of x` results in the static
compile-time type.
There is no dynamic type of a type instance since this would result in an
endless hierachy of types. So for Type values, dynamic_type is redefined
to just return Type.type.
equal to `type_of x`, but for `x` with a `ref` type `x.dynamic_type` gives
the actual runtime type, while `type_of x` results in the static
compile-time type.
There is no dynamic type of a type instance since this would result in an
endless hierachy of types. So for Type values, dynamic_type is redefined
to just return Type.type.
This enables a very idiomatic way of error handling: assume you are trying
to read 42 bytes from a file into a string. Let open be a feature that takes
a file name and returns an outcome of some abstract file descriptor, let read
be a feature that takes an abstract file descriptor and a number of bytes to
read and returns an outcome of a byte (u8) array. We want to read 42 bytes
from a file called "example.txt" into a string, and we wrap this into an outcome,
for handling the case that an error occurs when opening the file (i.e. it does
not exist) or when reading the file (i.e. example.txt is not actually a file but
a directory). Using match expressions, this is very cumbersome:
The monadic operator turns this into: