-- An example gidl IDL.
-- Line comments are haskell style.
{- Block comments are haskell style, as well. -}

-------------------------------------------------------------------------------
-- Type language
-------------------------------------------------------------------------------

-- All types end with a _t suffix in gidl syntax. Code generators may elect to
-- drop the _t suffix when generating type definitions.

-- Newtype definitions create a distinct type by wrapping an existing atomic,
-- enum, or newtype.
(def-newtype time_micros_t sint64_t)

-- Enums are pairs of names and integer values. Must be a one-to-one
-- mapping: names are not repeated, values are not repeated.
-- Enums default to 8 bit width if you don't really care.
-- N.B. we should probably change it to default to the smallest
-- width that fits the values the user declared.
(def-enum mode_t
 (stabilize 0)
 (auto 1))

-- The user can specify a bit width for enums with the
-- following syntax. 8, 16, 32, 64 bit widths are valid.
-- Integer literals can use any haskell integer literal format
(def-enum (armed_t 32)
 (disarmed 0)
 (armed 0x80000000))

-- Structures are a set of pairs of names and types. All
-- names must be distinct. All types must be atomic, enum,
-- or newtypes.
(def-struct heartbeat_t
 (time time_micros_t)
 (armed armed_t)
 (err   bool_t))

-- Definitions may be out of order. Circular definitions
-- are not permitted.
(def-struct coordinate_t
 (lat lat_t)
 (lon lon_t)
 (alt meters_t))
(def-newtype lat_t sint32_t)
(def-newtype lon_t sint32_t)
(def-newtype meters_t float_t)

-- Structures may contain structures.
(def-struct timed_coord_t
  (coord coordinate_t)
  (time time_micros_t))

-------------------------------------------------------------------------------
-- Interface language
-------------------------------------------------------------------------------

-- Here is an interface which defines a single stream named heartbeat.
(def-interface vehicle_i ()
 (heartbeat (stream heartbeat_t)))

-- Type definitions may be interspersed with interface definitions
(def-enum light_mode_t
  (off  0)
  (blink_slow 1)
  (blink_fast 2)
  (on 3))

-- Here is an interface which defines a single attribute. Attributes
-- may be given read, write, or readwrite access.
(def-interface light_i ()
  (light_mode (attr readwrite light_mode_t)))

-- Interfaces may be extended (subtyped). No shadowing of method
-- names permitted.
-- This interface extends the vehicle_i and light_i interfaces,
-- and defines two additional attributes.
(def-interface controllable_vehicle_i (vehicle_i light_i)
  (current_waypoint (attr read      coordinate_t))
  (next_waypoint    (attr readwrite timed_coord_t)))