When I discovered that python has parallel assignment I thought is pretty cool.
Recently I discovered parallel assignment works also in ruby.
For people that don’t know it: x,y = y,x in ruby, python this swaps x and y values .
Which language came first with parallel assignment, python? or was it other language?
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CPL introduced the feature in 1963, calling it simultaneous assignment. From D.W. Barron et al., “The main features of CPL” (page 140):
24. Simultaneous assignment commands
The general form of an assignment command can now be given. Normally this is an expression yielding an LH value, followed by :=, followed by an expression yielding an RH value. However, if an explicit list is written on the left-hand side then the right-hand side is either an explicit list, or a list expression; in the latter case the transfer function Members is automatically invoked. In this form the two explicit lists must contain the same number of members, and the command denotes a simultaneous assignment of each right-hand member to the corresponding left-hand member. Thus, if L is a list variable and a, b, c are real variables,
L := a, b, c
is an assignment to the list variable, while
a, b, c := L
a, b := b,a
are simultaneous assignments.
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