This convention is also used in Smalltalk, where only the special objects and can be used in a boolean expression.

Executing one of two subprograms according to the value of a boolean expression (selection)

Executing a subprogram until a boolean expression is true (iteration)

The boolean expression must be a compile-time constant value, for example would be a valid expression in that context.

TEX did not provide and or or connecters to make more complex boolean expressions.

A conditional is either a (boolean) expression and a process (b P) or an IF construct.

These terms can be used to write a minimal boolean expression representing the required logic.

The point is simply classified against all the underlying primitives and the resulting boolean expression is evaluated.

Using the for statement and a boolean expression:

Conditionally show or hide an element, depending on the value of a boolean expression.