Precompile the first calls of a JuliaCall session (#837)

A new JuliaCall session usually starts with `jl.<name>` on `juliacall.Main` or `jl.seval(...)`. PythonCall's package image had no compiled code for either method, so every session compiled them at runtime, which took about a second.

Co-authored-by: Miles Cranmer <miles.cranmer@gmail.com>
Co-authored-by: Christopher Rowley <cjdrwly@gmail.com>

Author: 3 people

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Changelog
 
 ## Unreleased
+* Improved TTFX in JuliaCall.
 * Minimum supported Python version is now 3.11.
 
 ## 0.9.37 (2026-10-12)

src/JlWrap/any.jl

@@ -21,6 +21,8 @@ function pyjlany_getattr(self, k_::Py)
     Py(getproperty(self, k))
 end
 pyjl_handle_error_type(::typeof(pyjlany_getattr), self, exc) = pybuiltins.AttributeError
+# `jl.<name>` on `juliacall.Main` is often the first call of a JuliaCall session.
+precompile(pyjlany_getattr, (Module, Py))
 
 function pyjlany_setattr(self, k_::Py, v_::Py)
     k = Symbol(pyjl_attr_py2jl(pyconvert(String, k_)))

src/JlWrap/module.jl

@@ -12,6 +12,8 @@ end
 function pyjlmodule_seval(self::Module, expr::Py)
     Py(Base.eval(self, Meta.parseall(strip(pyconvert(String, expr)))))
 end
+# `jl.seval(...)` is often the first call of a JuliaCall session.
+precompile(pyjlmodule_seval, (Module, Py))
 
 function init_module()
     jl = pyjuliacallmodule