Eslang

Is a Concatenative Stack-Oriented Programming Language

CLI

By default the CLI will read from a file called 01-input.esl, but you can use the -f flag to specify another path

$ go run main.go -f test.esl

Toc

• Push operations
• Arithmetic operations
• Relational operations
• Logical operations
• Stack operations
• Blocks
  • Conditions
  • Loops
• Variables

Push operations

Operation	Syntax	Description
OP_PUSH_INT	378	Push a 64 bytes int onto the stack
OP_PUSH_FLOAT	3.78	Push a 64 bytes float onto the stack
OP_PUSH_BOOL	true	Push a boolean onto the stack
OP_PUSH_STRING	"Hello World"	Push a string onto the stack

Large integer numbers can divided by an undercore _ to make them more readable: 1_000, 100_000

Top ▲

Arithmetic operations

Operation	Syntax	Description
OP_OPERATOR_ADD	+	Push the addition of the two topmost values on the stack onto the stack
OP_OPERATOR_SUB	-	Push the subtraction of the two topmost values on the stack onto the stack
OP_OPERATOR_MUL	*	Push the multiplication of the two topmost values on the stack onto the stack
OP_OPERATOR_DIV	/	Push the division of the two topmost values on the stack onto the stack
OP_OPERATOR_MOD	%	Push the modulo of the two topmost values on the stack onto the stack

Top ▲

Relational operations

Operation	Syntax	Description
OP_R_OPERATOR_EQUAL	=	Push the equal comparition between the two topmost values on the stack onto the stack
OP_R_OPERATOR_NOT_EQUAL	!=	Push the not equal comparition between the two topmost values on the stack onto the stack
OP_R_OPERATOR_LESS_THAN	<	Push the less than comparition between the two topmost values on the stack onto the stack
OP_R_OPERATOR_LESS_THAN_OR_EQUAL	<=	Push the less than or equal comparition between the two topmost values on the stack onto the stack
OP_R_OPERATOR_GREATER_THAN	>	Push the greater than comparition between the two topmost values on the stack onto the stack
OP_R_OPERATOR_GREATER_THAN_OR_EQUAL	>=	Push the greater than or equal comparition between the two topmost values on the stack onto the stack

Top ▲

Logical operations

Operation	Syntax	Description
OP_L_OPERATOR_AND	&&	Push the logical or between the two topmost values on the stack onto the stack
OP_L_OPERATOR_NOT	!	Push the logical and between the two topmost values on the stack onto the stack
OP_L_OPERATOR_OR	||	Push the logical not between the two topmost values on the stack onto the stack

Top ▲

Stack operations

Operation	Syntax	Examples	Description
OP_DROP	drop	( a -- )	Drops the top of the stack
OP_DUMP	dump	( a -- )	Dumps the stack
OP_DUP	dup	( a -- a a )	Duplicates the top of the stack
OP_NIP	nip	( a b -- b ) swap drop	Drops the second-to-top element of the stack
OP_OVER	over	( a b -- a b a )	Duplicate the second-to-top of the stack
OP_O_ROT	rot	( a b c -- b c a )	Rotates the top three elements of the stack
OP_ROT	-rot	( a b c -- c a b ) rot rot	Rotates the top three elements of the stack in the opposite direction
OP_SWAP	swap	( a b -- b a )	Swaps the top two elements of the stack
OP_TUCK	tuck	( a b -- b a b ) swap over	Duplicates the top of the stack and places it below the second-to-top
OP_TWO_DROP	2drop	( a b -- )	Drops the top two items from the stack
OP_TWO_DUP	2dup	( a b -- a b a b ) over over	Duplicates the top two elements of the stack
OP_TWO_OVER	2over	( a b c d -- a b c d a b )	Duplicates the second-to-top two items to the top of the stack
OP_TWO_SWAP	2swap	( a b c d -- c d a b )	Swaps the second-to-top two items on the stack
OP_DEBUG	debug	( a b -- a b )	Prints the stack

Top ▲

Blocks

Conditions

For now, Eslang have if-else conditions, In the future, I'm plaing to add switch conditions, but I have no itention to add if-elif-else conditions. This decision is maily to keep the language as simple as posible.

If-else

true if
    "Hello world from if condition" dump
end

Top ▲

Loops

While

10 while dup 0 > do
    dup dump
    1 -
end

Top ▲

Variables

To use a variable, we need to give it a name and a type, with following syntax

counter int

Where counter is the variable name and int is the variable type

By default variables will have a zero value.

Type	Zero value
int	0
float	0.0
bool	false
str	""

Variables operations

Operation	Syntax	Example	Description
OP_VARIABLE	counter	counter dump	Create a variable if it doesn't exist and push it to the stack
OP_VARIABLE_WRITE	.	counter 1 .	Write the value top of the stack to a variable in the second top of the stack