Returns a new Assignment stack, the result of prepending Assignment a.
Return the value assigned to variable v, or throw an Error if the variable is not in this Assignment.
Return the value assigned to variable v, or throw an Error if the variable is not in this Assignment.
Return true if this Assignment has a value for variable v.
Return true if this Assignment has a value for variable v.
Return the an Option for the value assigned to variable v.
Return the an Option for the value assigned to variable v. If v is not contained in this Assignment return None.
Return the an Option for the value assigned to variable v.
Return the an Option for the value assigned to variable v. If v is not contained in this Assignment return None.
Set variables to the values specified in this assignment
Set variables to the values specified in this assignment
All variables with values in this Assignment
All variables with values in this Assignment
An Assignment backed by a sequence of assignments. The returned value will be from the first Assignment in the sequence to contain the variable.