Section 6: Subprograms
{subprogram}
{procedure}
{function}
A subprogram is a program unit or intrinsic operation
whose execution is invoked by a subprogram call. There are two forms
of subprogram: procedures and functions. A procedure call is a
statement;
a function call is an expression and returns a value. The definition
of a subprogram can be given in two parts: a subprogram declaration defining
its interface, and a
subprogram_body
defining its execution. [Operators and enumeration literals are functions.]
To be honest: A function call is an expression,
but more specifically it is a
name.
Glossary entry: {Subprogram} A
subprogram is a section of a program that can be executed in various
contexts. It is invoked by a subprogram call that may qualify the effect
of the subprogram through the passing of parameters. There are two forms
of subprograms: functions, which return values, and procedures, which
do not.
Glossary entry: {Function} A function
is a form of subprogram that returns a result and can be called as part
of an expression.
Glossary entry: {
Procedure} A
procedure is a form of subprogram that does not return a result and can
only be called by a
statement.
{callable entity}
A
callable entity is a subprogram or entry
(see Section 9).
{call} A
callable entity is invoked by a
call; that is, a subprogram call
or entry call.
{callable construct}
A
callable construct is a construct that defines
the action of a call upon a callable entity: a
subprogram_body,
entry_body,
or
accept_statement.
Ramification: Note that “callable
entity” includes predefined operators, enumeration literals, and
abstract subprograms. “Call” includes calls of these things.
They do not have callable constructs, since they don't have completions.
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