zoomy_core.symbolic.sp_safe module

Held-form sympy constructors for the symbolic primitive layer.

Sympy’s default constructors auto-evaluate where they can: sp.Derivative(x**2, x) returns 2*x, not a held atom. This auto-evaluation is the root of every “math fired at the wrong pipeline position” bug we’ve hit — the framework can’t keep an opaque atom opaque if sympy decides to evaluate it on construction.

The constructors here always pass evaluate=False. Every primitive in this package must use them when it constructs a fresh Derivative, Integral or Subs atom. A CI grep forbids bare sp.Derivative(...), sp.Integral(...), sp.diff(...) calls inside the symbolic subpackage.

zoomy_core.symbolic.sp_safe.D(expr, *vars)

Held Derivative(expr, *vars).

Parameters:

• expr (sympy.Expr) –

• *vars – Each entry is either a single Symbol (∂_v applied once) or a (symbol, n) tuple (∂_v^n). Same shape sympy’s Derivative accepts.

Returns:

Always held — never auto-evaluated. The primitive layer decides when to apply chain/product/Leibniz rules.

Return type:

sympy.Derivative

zoomy_core.symbolic.sp_safe.Int(integrand, *limits)

Held Integral(integrand, *limits).

Each limit is either a bare Symbol (indefinite integral, single arg) or a (symbol, lower, upper) triple (definite integral).

sp.Integral is held by default (it never auto-evaluates on construction), so this is a thin documenting wrapper. Only .doit() or sp.integrate(...) would evaluate it — both are forbidden inside the symbolic package.

zoomy_core.symbolic.sp_safe.Sub(expr, var, value)

Held Subs(expr, var, value).

sp.Subs is held by default, so this is a thin alias that documents intent: any “evaluate expr at var = value” should go through Sub and produce a held atom rendered as expr|_{var=value} by the latex printer.

The primitive UnSubs is the only thing that may unwrap this.

zoomy_core.symbolic.sp_safe.held_function(name, *args, **kwargs)

Construct a held UndefinedFunction call f(*args).

A passthrough wrapper for completeness — sympy’s default behaviour on UndefinedFunction calls is already non-evaluating, so this is just sp.Function(name)(*args).