def x [square] x2 =
  x x * x2.
def x y [hypot2] out =
  x [square] x2;
  y [square] y2;
  x2 y2 + out.
def x y [hypot] h =
  x y [hypot2] h2;
  h2 [sqrt] h.
def p0 p1 x [lerp] p =
  1 x - ix;
  p0 ix * v0;
  p1 x * v1;
  v0 v1 + p.
def in [old] out =
  in [put state];
  [get state] out.
def in coeff [lowpass1p] out =
  out [old] oldout;
  oldout in coeff [lerp] out.
def in coeff [highpass1p] out =
  in coeff [lowpass1p] lowpassed;
  in lowpassed - out.
def phaseinc [phaseacc] out =
  [get phase] oldphase;
  oldphase phaseinc + newphase;
  newphase 1 > mustwrap;
  newphase mustwrap - wrappedphase;
  wrappedphase [put phase].