For each pervasive type the standard library provides one type specific I/O module. In order to facilitate the use of pervasive macros READ and WRITE, the type specific modules are named identical to their respective types.

• IO Module BITSET
• IO Module BOOLEAN
• IO Module OCTET
• IO Module CHAR
• IO Module UNICHAR
• IO Module CARDINAL
• IO Module LONGCARD
• IO Module INTEGER
• IO Module LONGINT
• IO Module REAL
• IO Module LONGREAL

The modules have to be imported directly or indirectly in order to use the pervasive macros READ and WRITE.

MODULE Example1;

FROM FileIO IMPORT File;

IMPORT CHAR; (* explicit import of CHAR's I/O module *)

VAR file : File; ch : CHAR;

BEGIN
    ...

    READ( file, ch );   (* equivalent to CHAR.Read( file, ch ); *)

    WRITE( file, ch );  (* equivalent to CHAR.Write( file, ch ); *)

END Example1.

Since it may be inconvenient to have to import each pervasive type's I/O module explicitly, the standard library should also provide a consolidated module that can serve as an import aggregator if desired. A module named PervasiveIO can be provided to serve this function.

MODULE Example2;

FROM FileIO IMPORT File;

IMPORT PervasiveIO; (* implicit import of all pervasive type I/O modules *)

VAR file : File; ch : CHAR;

BEGIN
    ...

    READ( file, ch );   (* equivalent to CHAR.Read( file, ch ); *)

    WRITE( file, ch );  (* equivalent to CHAR.Write( file, ch ); *)

END Example2.