The Smile Programming Language

Smile is an esoteric language based on deque (double-ended queue).

Data model

A Smile processor has one deque of (unlimited size of) integers.

Syntax

Numeric literals

• -11 : (-1 (-1
• -10 : (-1 (-0
• ...
• -2 : (-2
• -1 : (-1
• 0 : (-0 or 0-)
• 1 : 1-)
• 2 : 2-)
• ...
• 9 : 9-)
• 10 : 1-) 0-)
• 11 : 1-) 1-)

Note: (-1 2-) is parse error.

Arithmetic operations

• (+: :+) add_left/add_right

• (-: :-) sub_left/sub_right

• (*: :*) mul_left/mul_right

• (-/ /-) div_left/div_right

• (-% %-) mod_left/mod_right

• (-| |-) bitor_left/bitor_right

• (-& &-) bitand_left/bitand_right

• (^: :^) bitxor_left/bitxor_right

• (-! !-) not_left/not_right

comparison

• <-: :-< greater_left/greater_right
• >-: :-> less_left/less_right
• <=: :=< ge_left/ge_right
• >=: :=> le_left/le_right
• (=: :=) equal_left/equal_right

Deque operations

• p-: NUMBER push NUMBER to the left side of deque
• :-p NUMBER push NUMBER to the right side of deque
• s-: :-s swap_left/swap_right
• (": :") dup_left/dup_right
• D-: :-D discard_left/discard_right
• o-8 8-o rotate_left/rotate_right

I/O

• o-: :-o putc_left/putc_right
• O-: :-O putn_left/putn_right (capital o)
• i-: :-i getc_left/getc_right
• I-: :-I getn_left/getn_right (capital i)

Comments

• :-x single-line comment (to the end of the line)
• x-: single-line comment (to the beggining of the line)
• :-X ... X-: multi-line comment

Control flow

if (left)

• {-: (then) :-| (else) :-} pop a value from left. evaluate (then) if it is nonzero, evaluate (else) if it is zero.

if (right)

• :-{ (then) :-| (else) }-: pop a value from right. evaluate (then) if it is nonzero, evaluate (else) if it is zero.

Note 1: :-| and (else) may be omitted.

Note 2: |-: is the same as :-|.

while (left)

• [-: (body) :-] pop a value from left. if it is zero, break from loop.

while (right)

• :-[ (body) ]-: pop a value from left. if it is zero, break from loop.

exit

• B-) : Bye (terminates program)

Note: (-B is the same as B-).

Discussion

Turing completeness

If Brainf*ck can be implemented in Smile, Smile is Turing-complete.

Brainf*ck has these instructions:

• • ->
• • : dec
• . : out
• , : in
• : loop
• < : prev

• : next

case in when + :-p 1-) :+) when - :-p 1-) :-) when . :-o when , :-i when < when > when [ when ] end

| 0 3 2 5
^

2 5 (|) 0 3

| 0 3 2 5
^

5 (|) 0 3 2

| 0 3 2 5 0 ^

  (|) 0 3 2 5 0