Positionally is a 2d language in which only the presence and lack of commands matter. What command is executed depends on the instruction pointer's location.

IPs are spawned at the @ instruction in the grid below, if this doesn't exist one is spawned at (0, 0).

//<v>v\\
/012345\
>6789&|^
^+-*%d@<
>?.,:"$v
v()~{};<
\=sjpgS/
\\^<^>//

This grid repeats forever, so the IP's x/y are taken modulo 8 to get the commands.

<>^v\/ - Turns the IP or mirrors the IP.
0-9 - Pushes 0-9 onto the stack.
+-*%d - Maths operations.
@ - an IP starts here, going right.
? - Take input terminated with 0, cycling.
. - Print as char.
, - Print as num.
: - Duplicate.
" - stringmode (record nonspaces until next at pos).
$ - Swap the top elements of the stack.
() - less/greater than.
~ - Pop and ignore.
{} - Roll the stack left/right.
; - Terminate IP.
= - Test equality.
s - Skip next op if nonzero.
j - Pop two numbers x,y and jump to x,y (note: IP moves after jump) p - Pop two numbers and an ord and put char.
g - Pop two numbers and get char at point.
S - Unconditionally skip next instruction.
&| - push/pop global stack.