This is an attempt to formalize the type system of HLVM.

Basic Types

The following unboxed basic types are supported :

• i8 and ui8, size : 1 byte
• i16 and ui16, size : 2 bytes
• i32 and ui32, size : 4 bytes
• i64 and ui64, size : 8 bytes
• float, size : 4 bytes
• double, size : 8 bytes
• inat and uinat, size : 4/8 bytes (system dependent)
• bool, size : 4 bytes ???
• void, size : 4 bytes ???

Structural Types

Array

'a array : resizable array containing uniform types. The memory structure is {type*,ui32,void*}

• type* : a pointer to the type of the array content
• ui32 : the length of the array
• void*: the elements of the array

The following APIs can be use on arrays :

• $aalloc : ui32 -> 'a -> 'a array : allocate a new array with a default value
• $aget : 'a array -> ui32 -> 'a : read an element from an array, an exception occurs if bounds checking fails
• $aset : 'a array -> ui32 -> 'a -> void : write an element into
• $asize : 'a array -> ui32 : returns the size of the array
• $resize : 'a array -> ui32 -> 'a -> unit : resize the array by filling with a default value

Ref

'a ref : a reference to a given value. Memory size is 2 words, the memory structure is {type*,'a*}.

• $ralloc : 'a -> 'a ref : allocate a reference
• $rget : 'a ref -> 'a : get the reference value
• $rset : 'a ref -> 'a -> unit : set the reference value

Tuple

('a, 'b, 'c....)

Function

'a -> 'b -> 'c ....

Union

'a | 'b | 'c ...

{type*,uinat tag, ... }