sequence -- make a sequence

Synopsis

Usage:
sequence v
Inputs:
- v, a thing
Outputs:
- a sequence, v if v is a sequence, otherwise a sequence of length 1 containing v

Such a function is needed occasionally to restore uniformity, because a nonempty parenthesized expression with no commas is not parsed as a sequence.

i1 : sequence()

o1 = ()

o1 : Sequence

i2 : sequence(4)

o2 = 1 : (4)

o2 : Sequence

i3 : sequence(4,5)

o3 = (4, 5)

o3 : Sequence

i4 : identity()

o4 = ()

o4 : Sequence

i5 : identity(4)

o5 = 4

i6 : identity(4,5)

o6 = (4, 5)

o6 : Sequence