Cannot compute least sort of term (where the terms are lists)

Question

I have the following productions:

syntax Id
syntax Exp ::= Id
syntax Exps ::= List{Exp, ","}
syntax Ids ::= List{Id, ","}

What does this error mean?

[Error] Critical: Cannot compute least sort of term:
_,__KOOL-UNTYPED-SYNTAX(Id(#"x"),, .List{"_,__KOOL-UNTYPED-SYNTAX"}(.KList)).
Possible sorts are [Ids, Exps], but their least common subsort is
GeneratedListBottom{_,__KOOL-UNTYPED-SYNTAX}, which is not a possible sort.All
terms must have a unique least sort; consider assigning unique KLabels to
overloaded productions/completing the subsort lattice.
  while evaluating function project:Stmts
  while evaluating function initKCell
  while evaluating function initThreadCell
  while evaluating function initThreadsCell
  while evaluating function initTCell

nishantjr · Accepted Answer · 2022-07-12T18:50:20.333

3

K is not sure whether the term x, .List is an Ids or an Exps.

We want to tell K that:

All Lists of Ids are Lists of Exps:
```
syntax Exps ::= Ids
```
Lists of Ids with the same elements as a list of Exps are the same. We tell K that Exps and Ids parse to the same AST node using the klabel attribute:
```
syntax Exps ::= List{Exp, ","} [klabel(exps)]
syntax Ids ::= List{Id, ","} [klabel(exps)]
```

edited Jul 12 '22 at 18:50

answered Apr 10 '20 at 23:59

nishantjr

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Cannot compute least sort of term (where the terms are lists)

1 Answers1