brainfuck.sql

with recursive zero100(z, i) as (
  values(0, 0)
  union all
  select 0, i+1 from zero100 where i+1 < 100
), vm(step, sout, pc, ins, p, mem, stack) as (
  values(0, '', 1, '+++++++++[>++++++++>+++++++++++>+++++<<<-]>.>++.+++++++..+++.>-.------------.<++++++++.--------.+++.------.--------.>+.',
    1, (select array_agg(z) from zero100), array[]::int[])
  union all
  select
  step + 1,
  case substring(ins, pc, 1)
  when '.' then
    chr(mem[p])
  else
    ''
  end,
  case
  when substring(ins, pc, 1) = ']' and mem[p] <> 0 then
    stack[1]
  else
    pc + 1
  end,
  ins,
  case substring(ins, pc, 1)
  when '>' then
    p + 1
  when '<' then
    p - 1
  else
    p
  end,
  (select array_agg(m) from (select
      case row_number() over ()
      when p then m + case substring(ins, pc, 1) when '+' then 1 when '-' then -1 else 0 end
      else m
  end as m
  from unnest(mem) as t(m)) as tmp
),
case substring(ins, pc, 1)
when '[' then
  pc || stack
when ']' then
  stack[2:array_length(stack, 1)]
else
  stack
end
from vm where pc <= char_length(ins)
)
select array_to_string(array_agg(sout), '') from vm;