problog_export does not support type annotated functions

[XVilka]

I have a code like this:

#!/usr/bin/env python3
from __future__ import unicode_literals
from typing import List
from problog.extern import problog_export

# -----------------------------------------------------------------------------
# ProbLog exports

# instruction_string(Architecture, Bits, Address, Bytes, Instruction).
@problog_export('+str', '+int', '+int', '+list', '-str')
def instruction_string(architecture : str, bits : int, address : int, bytelist : List) -> str:
    return "blah"

But if I ran instruction_string("x86", 32, 0, [142, 142, 142], A). it fails miserably:

λ query(instruction_string("x86", 32, 0, [142,142,142], A)).                                                                                                                                                                                 
Traceback (most recent call last):
  File "./PrologShell.py", line 123, in <module>
    repl(ProblogDb)
  File "./PrologShell.py", line 94, in repl
    print_status(ProblogDb)
  File "./PrologShell.py", line 64, in print_status
    result = get_evaluatable().create_from(ProblogDb).evaluate()
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/core.py", line 150, in create_from
    return ProbLog.convert(obj, cls, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/core.py", line 120, in convert
    next_obj = path[0](current_obj, path[1](**kwdargs), **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine.py", line 54, in ground
    return ground_default(model, target, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine.py", line 74, in ground_default
    propagate_evidence=propagate_evidence, labels=labels)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine.py", line 492, in ground_all
    self.ground_queries(db, target, queries)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine.py", line 453, in ground_queries
    target = self.ground(db, query, target, label=label)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine.py", line 301, in ground
    target, results = self._ground(db, term, target, silent_fail=False, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine.py", line 409, in _ground
    results = self.execute(clause_node, database=db, target=gp, context=context, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_stack.py", line 521, in execute
    is_root=is_root, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_stack.py", line 180, in eval
    return exec_func(node_id=node_id, node=node, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_stack.py", line 992, in eval_extern
    return self.eval_builtin(node=SimpleBuiltIn(node.function), **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_stack.py", line 995, in eval_builtin
    return self.eval_default(EvalBuiltIn, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_stack.py", line 999, in eval_default
    cleanup, actions = node()  # Evaluate the node
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_stack.py", line 2181, in __call__
    current_clause=self.current_clause)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_stack.py", line 2227, in __call__
    results = self.base_function(*args, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/extern.py", line 138, in _wrapped_function
    bound = check_mode(args, list(self._extract_callmode()), funcname, **kwdargs)
  File "/home/user/.penv/lib64/python3.7/site-packages/problog/engine_builtin.py", line 611, in check_mode
    raise CallModeError(functor, args, accepted, location=location)
problog.engine_builtin.CallModeError: Invalid argument types for call to 'instruction_string/5': arguments: ("x86", 32, 0, [142, 142, 142], X1), expected: (atom, integer, integer, fixed_list, var) or (atom, integer, integer, fixed_list, atom).

[anton3s]

The Python 'str' type is mapped to the Prolog 'atom' type.
The expression "x86" is not a valid atom, you should use 'x86' instead.
As far as I remember Prolog strings (i.e. double quoted) are not supported in ProbLog (yet).

[XVilka]

Changed the syntax to 'x86', but now get a different error:

raise ValueError("Function has keyword-only parameters or annotations)

[anton3s]

It seems problog_export expect positional arguments on the exported Python function.
Adding type annotations apparently changes them to keyword parameters.

[XVilka]

Thanks! Now it works. Created two separate issues:

• Support type annotations
• Support Prolog strings