Main.seval can't parse multiple toplevel blocks

[LilithHafner]

Affects: JuliaCall

>>> from juliacall import Main
>>> Main.seval("x = 1+1; println(x)")
2
>>> Main.seval("x = 1+1\n println(x)")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/x/.julia/packages/PythonCall/qTEA1/src/jlwrap/module.jl", line 25, in seval
    return self._jl_callmethod($(pyjl_methodnum(pyjlmodule_seval)), expr)
       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
juliacall.JuliaError: Base.Meta.ParseError("extra token after end of expression")
Stacktrace:
 [1] parse(str::String; raise::Bool, depwarn::Bool)
   @ Base.Meta ./meta.jl:272
 [2] parse
   @ ./meta.jl:266 [inlined]
 [3] pyjlmodule_seval(self::Module, expr::Py)
   @ PythonCall ~/.julia/packages/PythonCall/qTEA1/src/jlwrap/module.jl:13
 [4] _pyjl_callmethod(f::Any, self_::Ptr{PythonCall.C.PyObject}, args_::Ptr{PythonCall.C.PyObject}, nargs::Int64)
   @ PythonCall ~/.julia/packages/PythonCall/qTEA1/src/jlwrap/base.jl:62
 [5] _pyjl_callmethod(o::Ptr{PythonCall.C.PyObject}, args::Ptr{PythonCall.C.PyObject})
   @ PythonCall.C ~/.julia/packages/PythonCall/qTEA1/src/cpython/jlwrap.jl:47

The issue here, I suspect, is that JuiliaCall uses a parsing method that accepts only a single top-level block. This is not ideal as Julia's eval ∘ Meta.parse accepts any number top-level expressions. What makes this a bug, though, is how subtle the difference between a single top-level block and multiple top-level blocks is. Specifically a; b is okay but a\nb is not which is very bad.

Fixing this may also fix #379 which would allow us to revert #380

[cjdoris]

If we're being pedantic about it this isn't a bug: a;b really is a single block expression (this is the documented meaning of ;) whereas a\nb is just two expressions separated by whitespace, which don't become a single expression until wrapped in some higher block such as begin ... end.

Anyway I totally agree that seval should support multiple expressions.

[MilesCranmer]

Can I help add this? This is a blocker for MilesCranmer/PySR#535

[MilesCranmer]

Ah it looks like the fix is just Meta.parse -> Meta.parseall.

Edit: fixed in #452