* Formicidae assembly code

Formicidae assembly files begin with a line containing the number of
states in them.  Following that is that number of states.  Finally, it
contains a possibly empty sequence of aliases, or lists of two elements
denoting that the first element is an alias for the state indexed in
the current file by the second element.

A Formicidae state is a list of at least two elements in the form:

(<state-id> <operator> (<continuation> ...) <operand> ...)

STATE-ID is a symbol or #F denoting the identifier of the state, to be
used during state linking.  Each CONTINUATION is a zero-based index to
a state in the same brain, or a symbol denoting the name of a state
which has not yet been linked.  The precise details of each  OPERAND
are specific to the operator.

(SENSE (<success> <failure>) <direction> <attribute>)
  Sense in DIRECTION for ATTRIBUTE.  DIRECTION is a symbol in the set
  {HERE, AHEAD, LEFT, RIGHT}; ATTRIBUTE is either an integer in the
  range [0,7) or a symbol in the set {FRIEND?, FOE?, HOME?, FOE-HOME?,
  FRIEND-WITH-FOOD?, FOE-WITH-FOOD?, FOE-MARK?, FOOD?, ROCK?, WATER?}.
  If the specified attribute is found to be in the cell in DIRECTION,
  control jumps to SUCCESS; if not, it jumps to FAILURE.

(TURN (<target>) <direction>)
  Turn the ant in DIRECTION, which should be either the symbol LEFT or
  the symbol RIGHT.  Control jumps unconditionally to TARGET.

(MOVE (<success> <failure>))
  Attempt moving forward.  If there is an ant or a rock in front of the
  ant, control jumps to FAILURE; if there is water in front of the ant,
  the ant dies; otherwise, control jumps to SUCCESS.

(PICK-UP (<success> <failure>))
  Attempt picking up food.  If there is food to pick up, control jumps
  to SUCCESS; otherwise, control jumps to FAILURE.

(DROP (<target>))
  If there is food to drop, drop it on the current hex.  Control jumps
  unconditionally to TARGET.

(MARK   (<target>) <index> <amount>)
(UNMARK (<target>) <index>)
  Mark or unmark the pheromone flag indexed by INDEX for the current
  ant's team on the current hex.  <amount> specifies the amount of pheromone
  deposited, a.  For each unit of pheromone, the marker will persist for 
  50 ticks.  This operation takes one tick for each 100 units of pheromone, 
  with a one tick minimum.  Control jumps unconditionally to
  TARGET.  Unmarking a pheromone completely neutralizes any pheromone
  on the cell, regardless of amount.

(FLIP (<left> <right>) <p>)
  If a random integer between [0,p) is zero, control jumps to LEFT;
  otherwise, it jumps to RIGHT.  P should be an integer greater than
  zero and representable in twelve bits, i.e. in the range [1,4096).  A
  P of 1 is acceptable, but not very useful.

All operands should be literal constants; no operands are evaluated for
their value.  Operand evaluation should have occurred in compilation.