unsequence -- extract the single element from a sequence of length 1

• Usage:

  unsequence x

• Inputs:
  • x, a thing
• Outputs:
  • x#0, if x is a sequence of length 1, otherwise x

i1 : unsequence (2:a)

o1 = (a, a)

o1 : Sequence

i2 : unsequence (1:a)

o2 = a

o2 : Symbol

i3 : unsequence (0:a)

o3 = ()

o3 : Sequence