Programming Language for Old Timers

by David A. Moon
February 2006 .. September 2008

Comments and criticisms to dave underscore moon atsign alum dot mit dot edu.

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Typed Variables

The syntactic type typed-variable is defined in the compiler module. It has slots for name and type. The name is the name of a variable. The term "variable" is used for traditional reasons, although almost all uses of typed-variable create fixed definitions, so the "variable" cannot actually vary. The type is an expression that must evaluate to a type. The value of the variable is restricted to be a member of this type.

The syntax for a typed-variable is a variable name optionally followed by the bound particle is and a type specifier (see the next section). If just a variable name is specified with no type restriction, the type defaults to anything.

A variable name consists of either a name that is not punctuation and is not visibly defined as an operator or macro, or a backslash followed by any name or a string that gets converted to a name.


def pi = 3.14159
def pi is float = 3.14159
def y is integer-above(0) or false := z
def w is 64 bits = 1234567890

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