Name Rascal/Expressions/Values/Set/Splice

Synopsis Splice the elements of a set in an enclosing set.

Syntax *Exp

Types

Exp	Exp1	Expn	{Exp1, ..., Exp, ..., Expn}
T	T1	Tn	set[lub(T1, ..., T, ...,Tn)]

Description The operator * splices the elements of a set in an enclosing set.

Examples Consider the following set in which the set {10, 20, 30] occurs as set element. It has as type set[value]:

rascal>{1, 2, {10, 20, 30}, 3, 4};
set[value]: {1,2,3,4,{10,20,30}}

The effect of splicing the same set element in the enclosing set gives a flat list of type set[int]:

rascal>{1, 2, *{10, 20, 30}, 3, 4};
set[int]: {1,2,3,4,10,20,30}

The same example can be written as:

rascal>S = {10, 20, 30};
set[int]: {10,20,30}
rascal>{1, 2, *S, 3, 4};
set[int]: {1,2,3,4,10,20,30}

Benefits The splicing operator gives full, explicit, control over the way in which nested sets are handled.

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