Spoofax 2.5.5 Migration Guide¶
A few changes in Statix need migration for specs written for older versions.
Statix¶
A few features in Statix were not well-defined and removed until a better way to support them is found. Therefore, the following changes may require you to make small modifications to a specification:
- Functional constraints can only have a single output.
- Regular expression and label order must be direct parameters to queries.
- Namespace based query short-hands require
- a literal occurrence as argument, and
- an explicit resolution policy entry.
Functional constraint outputs¶
Functional constraints previously were allowed to have multiple output arguments, such as:
f : T * T -> T * T`
This was sometimes indistinguishable from types with a single tuple output, such as:
f : T * T -> (T * T)`
From now on, functional constraints can only have a single output. Constraints with multiple outputs need to be rewritten to return a tuple instead.
Query parameters¶
Queries would accept arbitrary predicates for the label regular expression and label order. For example, a query could be written as:
query filter myWf and true
min myOrd and false
in s |-> _
with
myWf(ls) :- pathMatch[P*](ls).
myOrd(l1,l2) :- pathLt[$ < P](l1,l2).
This is not possible anymore, instead the regular expression and label order must be direct parameters of the query. The query above should be directly written as:
query filter P* and true
min $ < P and false
in s |-> _
The following syntax is still accepted, but deprecated:
query filter pathMatch[P*] and true
min pathLt[$ < P] and false
in s |-> _
Namespace-based resolution shorthands¶
The requirements for namespace-based resolution shorthands have become stricter.
First, if they are used, ther emust be an explicit resolution policy for the namespace. For example, using a constraints such as:
Var{x@-} in s |-> _
type of Var{x@-} in s |-> _
requires in the signature at least:
signature
name-resolution
resolve Var
A full resolution policy with regular expression and label order looks like this:
signature
name-resolution
resolve Var filter P* min $ < P
Second, the namespace-based constraints require an occurrence literal. The following does not work anymore:
d == Var{x@-},
d in s |-> _
The occurrence has to be repeated in the constraints, as:
Var{x@-} in s |-> _
Created: April 19, 2024