RETURN (my favorite stack type in DUP) is a stack-based language inspired by DUP. It is an attempt to improve upon DUP in a way that allows more programming tasks to be solved more easily.
RETURN is different from other stack-based languages in that there are multiple stacks. You get 2 parent stacks, and new children stacks can be created along the way. There are different commands to switch between and manipulate stacks.
RETURN uses ISO-8859-1.
0-9: Push number to stack. You may need to separate series of numbers with whitespace.\0: Find all indices of top item in stack, or return-1if not found.\1: Switch parent stacks.\2: Duplicate top n items into a new stack.\3: Reverse stack.\4: Transpose stack.\5: Flatten stack.\6: Sort stack.\7: Get stack length.\b: Concatenate top 2 items.\t: Split the stack into chunks.\n: Generate a range between top 2 numbers.\v: Repeat stack by top item.\f: Push to other parent stack.\x0e: Get top item from other parent stack.{: Set top item as current stack.}: Get out of current stack into surrounding stack.%: Drop top item.$: Duplicate top item.¤: Pick 2nd item from top.\: Swap top 2 items.@: Pull nth item to top.ª: Push item to nth index.ø: Duplicate nth item from top.+-×^: Add/subtract/multiply/pow top 2 items.÷: Divmod top 2 items (mod first, then div).¿: Push random binary number to stack.Ð: Push milliseconds elapsed since January 1, 1970 00:00:00 UTC.&|: Perform bitwise AND/XOR on top 2 items.~: Perform bitwise NOT on top item.«»: Perform logical left/right shift on top 2 items.±: Get sign of top item.<: Check if top item is less than 0.>: Check if top item is greater than 0.'a: Push subsequent charcode to stack."...": Push a series of charcodes to a new stack until another"is met.¦: Split a number into a stack with its individual digits.§: Join a stack into a number.¨: Split a stack along top item.°: Join stack with top item..: Output top item.,: Output top item as charcode.`: Push entire input into a new stack.:: Store 2nd item from top to top item.;: Get stored value from top item.¥: Coerces null to 0, and anything else to -1.[...]: Push lambda to stack.!: Execute lambda.[...][...]?: Executes 2nd lambda from top if 3rd item from top is truthy; otherwise, executes top lambda.[...][...]#: Executes top lambda while condition (returned by 2nd lambda from top) is truthy.[...]=a: Define top lambda as operator.
"Hello, world!":
"Hello, world!",
cat:
`,
Quine:
"34¤¤,,,,"34¤¤,,,,
Infinite loop:
~!
Factorial (requires input number to be on stack):
5 1+1␊␅[¤][×]#
Fibonacci Sequence (infinite loop):
1$[¤¤+2!]!
Thue-Morse Sequence (infinite loop):
0[␇␂{[$¥][[0][1]?␌]#[␎$¥][]#%}␅1!]!