! (goto)

gistfile1.txt

[1] (operator { postfix: ! } ({ a: Z64 } → Z64)
      ({ accumulator: Z64 } ← 1)

      { compute:
        (match [a]
          { 0: accumulator }
          { _: (accumulator ← (a × accumulator))

          (a ← (a − 1))
          
          (goto compute)})})
 
{ operator: { postfix: :! } ({ a: Z64 } → Z64) }
 
[2] 5!
 
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