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Task/Call-a-function/ALGOL-W/call-a-function.alg

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+% Note, in Algol W, functions are called procedures %
+% calling a function with no parameters: %
+f;
+
+% calling a function with a fixed number of parameters %
+g( 1, 2.3, "4" );
+
+% Algol W does not support optional parameters in general, however constructors for records can %
+% be called wither with parameters (one for each field in the record) or no parameters #
+
+% Algol W does not support variable numbers of parameters, except for the built-in I/O functions #
+% Algol W does not support named arguments %
+
+% A function can be used in a statement context by calling it, as in the examples above %
+
+% First class context: A function can be passed as a parameter to another procedure, e.g.: %
+v := integrate( sin, 0, 1 )
+% assuming a suitable definition of integrate %
+% Algol W does not support functions returning functions %
+
+% obtaining the return value of a function: e.g.: %
+v := g( x, y, z );
+
+% There is no syntactic distinction between user-defined and built-in functions %
+
+% Subroutines and functions are both procedures, a subroutine is a procedure with no return type %
+% (called a proper procedure in Algol W) %
+% There is no syntactic distinction between a call to a function and a call to a subroutine %
+% other than the context %
+
+% In Algol W, parameters are passed by value, result or value result. This must be stated in the %
+% definition of the function/subroutine. Value parameters are passed by value, result and value result %
+% are effectively passed by reference and assigned on function exit. Result parameters are "out" parameters %
+% and value result parameters are "in out". %
+% Algol W also has "name" parameters (not to be confused with named parameters). Functions with name %
+% parameters are somewhat like macros %
+
+% Partial application is not possible in Algol W %