⊦ ⌜x⌝ = ⌜hd(⌜x⌝ ) '⌝ + tl(⌜x⌝ ), ⌜x⌝ = []
⊦ ⌜nf⌝ = ⌜hd(⌜nf⌝ ) '⌝ + tl(⌜nf⌝ ), ⌜nf⌝ = []
Used simplifier rules: stream freely generated by ⌜ ⌝, ⌜ ⌝;;