Library Functions

Scheme_Object *scheme_invoke_unit(Scheme_Object *unit, int num_ins, 
               Scheme_Object **ins, Scheme_Object **anchors, int tail, int multi) 

Invokes a unit. The num_ins argument specifies the number of variables to import into the unit. The ins array must be an array of variables boxes (NULL if no variables are imported). The anchors argument is is parallel to the ins array, providing a garbage-collecting anchor for each variable. The scheme_invoke_unit function will check that the correct number of variables are provided for importing into the unit.

A variable box can be any pointer. The pointer is deferenced as a Scheme_Object ** to get the variable box's contents. Anchors are associated with variable boxes so that a box can point into the middle of an allocated array; in this case, the anchor would be the start of the array, so that the garbage collector sees a reference to the array.

If tail is non-zero, scheme_invoke_unit produces a tail-call to invoke the unit. If tail is zero and multi is non-zero, multiple values may be returned.

Scheme_Object *scheme_make_envunbox(Scheme_Object *v) 

Creates a new variable box with v as the initial value. No anchor is needed (i.e., NULL can be used as an anchor) for boxes created this way.

Scheme_Object *scheme_assemble_compound_unit(Scheme_Object *imports, Scheme_Object *links, 
               Scheme_Object *exports) 

``Compiles'' a compound-unit expression, given the names for the compound unit's imports, exports, and sub-unit linking.

• The imports argument is a Scheme list of symbols for the imported variable names.
• The links argument is a list of sub-unit linking specifications, where each specification is a pair consisting of:
  • a single tag symbol, used to identify the unit for links and re-exports
  • a list of variable specifications, where each variable specification is either
    • a symbol that is present in the imports list, specifying a link to a variable imported into the compound unit, or
    • pair consisting of a tag symbol and a list of symbols, specifying the names of exported variables from another sub-unit in the compound unit
• the exports argument is a list of sub-unit export specifications, where each export specification is a pair consisting of
  • a tag symbol
  • a symbol naming one export from the corresponding sub-unit (used as both the name of the sub-unit export and the name of the compound unit's export), or a pair of symbols where the first one is the name of the sub-unit's export and the second one is the name as exported from the compound unit

The return value is an ``assembled'' compound unit. A compound unit is created from the assembly with scheme_make_compound_unit.

Scheme_Object *scheme_make_compound_unit(Scheme_Object *assembly, Scheme_Object **subs) 

Returns a compound unit given an assembly created by scheme_assemble_compound_unit and an array of sub-units to be linked into the compound unit. The order of units in the sub-unit array should parallel the order of tags in the assembly's links specification.