fallible

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`

cause fault with the given error

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?

type feature that must be implemented by all children to create an
instance of `fallible.this.type` with the given error handler.

try -- run code and handle fault of type `fallible.this`.

try is a type feature that can be called on any child of `fallible`
to run the code given as an argument and handle an error using the
`Unary` provided to `catch`.

This enables Java-like try-catch syntax as follows

res := FALLIBLE_TYPE.try ()->

or even

res := FALLIBLE_TYPE.try code || (s->handle fialure `s`)

Note that the code is not executed unless `.catch` or `infix ||` is applied
to the result of the call to `try`.

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`.