calculus e ::= x x ∈ vp [value] | λx.e [lambda] | let x = e1 in e2 [let] | fix x.e [fixpoint] | e1 e2 [app] | if (ec ) et else ee [if ] | delay n e1 e2 n ∈ ℕ [delay] | feed x.e [feed] | ... τp ::= R [real] | N [nat] τ ::= τp | τ → τ [function] 7BMVFT 5FSNT vp ::= r r ∈ ℝ | n n ∈ ℕ v ::= vp | cls(λx.e, E) 5ZQFT