Mathematical Double-struck S (𝕊)

𝕊: Current Function

A variable assigned to the current function block. 𝕤 can be used to access the current function block as a subject.

𝕊 can be used for recursion.

    F ← {𝕊 0: 1; 𝕩 × 𝕊 𝕩-1} # Factorial
    F 5
120

    {𝕤‿𝕤}4
⟨ (function block) (function block) ⟩