Terrain
- This is still a work in progress. It may be changed in the future.
Terrain is an esoteric programming language by Grs (talk) that's meant to resemble (somewhat) natural looking terrain. It's written as text, though, so it could be considered as an ASCII drawing (or multiple) too.
Code structure
The code consists of ASCII drawing(s) of terrain and flowers. It consists of |, /, \, _ and X characters and spaces for alignment. The different changes in height determine the commands and possibly other data. However, the code doesn't have to be as a single terrain parts. There can be multiple in a file under each other. However, each must be the same height (each has to have the same number of lines). In these terrain parts, there can be empty lines without code. But if there are multiple terrain parts, these empty lines can be mandatory.
If there are multiple terrain parts under each other, they will be executed like if they were one single terrain part, top to bottom.
Spaces can be used to align the above mentioned characters in the lines. If there are lines that have some of those characters but don't end in one of them, you don't have to type spaces until the end of the line.
All other characters than |, /, \, _, X and a space are treated as spaces, except tabs. Tabs are treated as 4 spaces.
Flowers
Flowers are drawn like this above ground:
X X X | | | __________
Or simply just like this above ground:
X X X __________
Flowers cannot be drawn above any thing else other than _.
Terrain character alignment
Aligning terrain pieces means that the characters kind of make a line appear.
Rules:
- If there are two | next to each other, they are aligned like this:
| |
- If there are two / next to each other, they are aligned like this:
/ /
- If there are two \ next to each other, they are aligned like this:
\ \
- If there are two _ next to each other, they are aligned like this:
__
- / and _ (2 cases)
_/
_ /
- _ and \ (2 cases)
\_
_ \
Note: As you can see, some of these take up 2 lines, while some only take up 1 line. This can influence the change in height.
- / and \ (2 cases)
/\
\/
- / and | (2 cases)
/ |
| /
- \ and | (2 cases)
\ |
| \
- _ and | (4 cases)
_|
|_
_ |
_ |
Any other combinations are not allowed and an exception will be thrown.
Change in height explanation
Changes in height determine the commands and possibly other data. The change in height is determined in the following way.
1. Go forward until you hit a |, / or a \. 2. Count how many lines do you have to go up or down to hit at least 5 _ characters in a row (_____). Count upwards movement as +1 and downwards movement as -1. 3. The number you got is a change in height. It's a sum.
Examples
Thus this terrain part has a height change of 5:
_________ 5
/ 4
/ 3
/ 2
/ 1
_________/ 0
This also has a height change of 5:
_________ 5
/ 4
___/ 3
/ 2
/ 1
_________/ 0
This also has a height change of 5:
_________ 5
/ 4
___ / 3
/ \ / 2
/ \____/ 1
_________/ 0
This has a change of -2:
_____ 0
\ -1
\ _____ -2
\ /\ / (-3)
\ / \_/ (-4)
\____/ (-5)
Note: By the way, you don't have to write out those numbers when coding.
Multiple of these "changes in height" can be "chained" together.
Example:
_____ __ / \ ___________ \ / \________/ \_____/\__/
Where changes in height start and end?
Every change in height (thus commands and possibly other data) ends at _____ and those characters are in the command too. The characters directly after these count to the next command. The first some characters are always included in the first change in height, even if these characters are _____.
Example
In the example, < and > determine the start and the end of changes in height. The characters under < and > are also included in the specific change in height. The numbers are the change in height. -4 means 4 lines down in total. 8 means 8 lines up in total.
< -4 >< -2 >< 1 >< 2 >< 8 >< -3 >< 1 >< -1 >
_____
/ \
/ \ _____
/ \_____/ \_____
/
_ /
\ /
\ /
\ _____/
\_____ /
\ _____/
\_____/
Data and data storage
Terrain has a stack to which it can push data to and pop elements from. This stack can also be reversed. Only numbers are stored on this stack. Terrain can, however, output characters according to a character's ASCII value.
Programming
Commands are determined from the changes of height in the terrain when going from left to right in the file. When encountering a change in height and it's known that currently not an argument is being entered, it is interpreted as a command.
Every command must have at least 2 flowers. They, however, don't execute anything, except maybe serving as decoration.
Commands can also take arguments. Arguments can only be numbers. Arguments come directly after the command.
Unrecognized commands don't throw an error. The program just goes to the next command. However, you shouldn't give unrecognized commands arguments, because the program doesn't look for arguments after these commands and these arguments may make your program run incorrectly.
Commands
Argument requirements are shown between < and > characters.
| Change in height | Command name | Short description with parameters | Additional info |
|---|---|---|---|
| 0 | JMP | Define jump point <number> | Defines a jump point with a specified number. |
| -1 | JMPO | Define ordered jump point | Defines an ordered jump point. Ordered jump points are numbered starting from the start of the code going towards the end of the code. The ordering starts at 0. Each ordered jump point gets: the previous ordered jump point's number + 1. |
| -2 | JMPT | Jump to jump point with number <number> | Jumps directly to the next command after the jump point with the specified number. The jump point is specified by the "Define jump point <number>" command. |
| 1 | JMPTO | Jump to ordered jump point with place <number> | Jumps directly to the next command after the jump point with the specified number. The jump point is specified by the "Define ordered jump point" command. |
| 9 | BACK | Return | Jump to the command after the last "Jump to jump point with number <number>" or "Jump to ordered jump point with place <number>". These jumps are stored in a stack too. Thus, you can call this multiple times without jumping if ou have jumped multiple times before. Like: jump jump jump return jump return return return |
| 2 | PUSH | Push value <number> | Pushes the specified number onto the stack. |
| -3 | POP | Pop | Pop a value from the stack and discard. |
| 4 | POPNUM | Pop and print number | Pop a value and print as number. |
| 5 | POPCHR | Pop and print ASCII | Pop a value and print the ASCII character with that value. |
| -4 | INNUM | Take number input from the user | Takes input from the user and interprets it as a number and pushes this number onto the stack. |
| -5 | INCHR | Take character input from the user | Takes a character of input from the user and pushes the character's corresponding ASCII value onto the stack. |
| 10 | INLRSTR | Input left to right string | Take a string of characters from the user and push them to the stack from left to right. |
| -10 | INRLSTR | Input right to left string | Take a string of characters from the user and push them to the stack from right to left. |
| 7 | SKGT | Skip if greater than | Pop two values off the stack (first is a, second is b), if a > b, jump over next command. |
| 8 | SKLT | Skip if less than | Pop two values off the stack (first is a, second is b), if b > a, jump over next command. |
| 11 | ADD | Addition | Pop two values, add them, push result. |
| -11 | SUB | Subtraction | Pop two values (first is a, second is b), push b - a |
| 12 | MUL | Multiplication | Pop two values, multiply them, push the result. |
| -12 | DIV | Division | Pop two values (first is a, second is b), push b / a |
| -9 | MOD | Modulo | Pop two values (first is a, second is b), push b % a |
| 13 | EXP | Exponentiation | Pop two values (forst is a, second is b), push b ^ a |
| -13 | ROOT | Root | Pop two values (first is a, second is b), push the bth root of a (bva̅) |
| 3 | DUP | Duplicate | Duplicate the top value on the stack. (Has the effect of popping the value then pushing it twice.) |
| 14 | REV | Reverse | Reverse the stack |
| -14 | SWT | Switch places | Reverse the top 2 values on the stack. (Has the effect of these "switching places" in the stack.) |
| -15 | END | End | Stop the execution of the program. |
Defining numbers
Numbers are defined by multiple changes in height and these definitions are only accepted at some places (see the Commands section below).
The first change in height defines the base.
| Change in height | Base |
|---|---|
| -3 | 2 (binary) |
| -4 | 10 (decimal) |
| -5 | 16 (hexadecimal) |
If omitted, base 10 is used.
The second (possibly first if base is omitted) change in height defines the sign.
| Change in height | Sign |
|---|---|
| -2 | - (minus) |
| -1 | + (plus) |
If omitted, plus is used.
Then comes the number itself. The number is defined by multiple changes in height. These represent digits in the number or a floating point or the end of the number. You cannot start this part with a floating point and cannot end it with a floating point either.
| Change in height | Meaning |
|---|---|
| 0 - 16 (depending on base what is allowed) | Here is a digit with the value of the amount of changes in height |
| -2 - -∞ | A floating point should be placed here |
| -1 | Here is the end of the number |
At least one digit should be given, the floating point can be omitted.
Examples of numbers
-128.1 in decimal (all parts defined)
_____
/ \
/ \ _____
/ \_____/ \_____
/
_ /
\ /
\ /
\ _____/
\_____ /
\ _____/
\_____/
---- -- - -- -------- --- - -
BASE SIGN 1 2 8 POINT 1 END
Example programs
Note: Since there is no implementation yet, some or all of these programs may not be correct. Rather, take these as help for how a program MAY look like.
Truth-machine
UNFINISHED
TODO: Add flowers
_____
/ \
/ \
_____ _____ / \
_____/ \/ \_____/ \
/ \
/ \
/ \
/ \
/ \
/ \
_____ _____ / \
_____/ \/ \_____/ \
/ \
/ \
/ \_____
_____/
_____ /
_____/ \_____ /
_ / \_____/
\ _____/
\ /
\ /
\_____/