code_effect

replace effect in the current context by this and abort current execution

does this effect support abort?

Redefining this to return `false` helps to detect unexptected calls to
`abort` at runtime and ensure that the static analysis finds that the
code executed with this effect will always return normally and produce
a result. This is used, e.g, in `mutate` to avoid static analysis
reporting `panic` as an effect of the use of a local mutate instance.

create a String from this instance. Unless redefined, `a.as_string` will
create `"instance[T]"` where `T` is the dynamic type of `a`

the code to be executed within this effect. This is typically
redefined as an argument field of a sub-feature of effect.

NYI: Currently, there is no direct way to return a result value
from the code.

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.

name of this type, including type parameters, e.g. 'option (list i32)'.

convenience prefix operator to create a string from a value.

This permits usage of `$` as a prefix operator in a similar way both
inside and outside of constant strings: $x and "$x" will produce the
same string.

abort the current execution and return from the surrounding call to
abortable with result == false.

execute the code of 'f' in the context of this effect

has an effect of the given type been installed?

has an effect of the given type been installed?

Get a type as a value.

This is a feature with the effect equivalent to Fuzion's `expr.type` call tail.
It is recommended to use `expr.type` and not `expr.type_value`.

`type_value` is here to show how this can be implemented and to illustrate the
difference to `dynamic_type`.