Minecraft Function Plus

A high level general purpose programming language that compiles into mcfunction

Features

• Arithmetic expressions
  • int and bool only
• if / else statements
• while / for loops
• Functions
• Structs
• Import statements

Limitations

• No 'heap' or dynamic allocation
  • Variables are implemented via the scoreboard, which does not allow for dynamically generating new variables, so all variables must be defined at compile time
  • This means implementing a resizable list is not possible
• No recursive function calls
  • Because dynamic allocation is not possible, properties of recursive function calls cannot be stored. This could be rectified by allowing a fixed number of recursions, but I find that this defeats the purpose of supporting the feature, so I chose to leave it out.
• No floating point numbers, bytes
  • Minecraft supports storage of int8, int16, int32, int64, float32, and float64 values via the /data command. In order to perform arithmetic, these values must be copied to the scoreboard and are casted to int32
    • Vote here so Mojang adds floating point math: Add a math parameter to /data modify - Minecraft Feedback
  • Fixed point numbers are possible but I have not explicitly implemented them

Example

fib.mcfp

// Prints to chat the Fibonacci sequence up to n = 25, 46368

var a = 0;
var b = 1;

for (var n = 0; n < 25; n = n + 1) {
  var temp = a;
  a = b;
  b = temp + b;
  print temp;
}

Compiled in 10.89 ms with pretty and debug mode on.

Compiled mcfunction

fib.mcfunction

# Compiled by mcfp_dart 1.0

# RUNTIME SETUP

scoreboard objectives add mcfp_runtime dummy
scoreboard players reset * mcfp_runtime
scoreboard objectives setdisplay sidebar mcfp_runtime
scoreboard players set neg_one mcfp_runtime -1

# END RUNTIME SETUP
# WALKING SYNTAX TREE


# VAR
scoreboard players set fib_a mcfp_runtime 0

# VAR
scoreboard players set fib_b mcfp_runtime 1
execute if function mcfp:fib_91lozjus6a5b run return 1

# CLEAN
scoreboard players reset fib_a mcfp_runtime
scoreboard players reset fib_b mcfp_runtime
scoreboard players reset fib_91lozjus6a5b_n mcfp_runtime
scoreboard players reset fib_91lozjus6a5b_x3jf5nvq4k7h mcfp_runtime

# RUNTIME CLEAN
scoreboard players reset neg_one mcfp_runtime
scoreboard players reset return_value mcfp_runtime
scoreboard players reset should_break mcfp_runtime

fib_91lozjus6a5b.mcfunction

# VAR
scoreboard players set fib_91lozjus6a5b_n mcfp_runtime 0

# WHILE CONDITION
scoreboard players set fib_91lozjus6a5b_4y4atkm2319k mcfp_runtime 25
scoreboard players set fib_91lozjus6a5b_x3jf5nvq4k7h mcfp_runtime 0
execute if score fib_91lozjus6a5b_n mcfp_runtime < fib_91lozjus6a5b_4y4atkm2319k mcfp_runtime run scoreboard players set fib_91lozjus6a5b_x3jf5nvq4k7h mcfp_runtime 1
scoreboard players reset fib_91lozjus6a5b_4y4atkm2319k mcfp_runtime

# WHILE REPEAT
scoreboard players set should_break mcfp_runtime 0
execute if score fib_91lozjus6a5b_x3jf5nvq4k7h mcfp_runtime matches 1 run execute if function mcfp:fib_91lozjus6a5b_l1lcp73oc9te run return 1
scoreboard players reset fib_91lozjus6a5b_x3jf5nvq4k7h mcfp_runtime

fib_91lozjus6a5b_l1lcp73oc9te.mcfunction

# VAR
scoreboard players operation fib_91lozjus6a5b_l1lcp73oc9te_temp mcfp_runtime = fib_a mcfp_runtime

# ASSIGN
scoreboard players operation fib_a mcfp_runtime = fib_b mcfp_runtime

# ASSIGN
scoreboard players operation fib_91lozjus6a5b_l1lcp73oc9te_za0ysaxto51i mcfp_runtime = fib_91lozjus6a5b_l1lcp73oc9te_temp mcfp_runtime
scoreboard players operation fib_91lozjus6a5b_l1lcp73oc9te_za0ysaxto51i mcfp_runtime += fib_b mcfp_runtime
scoreboard players operation fib_b mcfp_runtime = fib_91lozjus6a5b_l1lcp73oc9te_za0ysaxto51i mcfp_runtime
scoreboard players reset fib_91lozjus6a5b_l1lcp73oc9te_za0ysaxto51i mcfp_runtime

# PRINT
tellraw @a [{"text":"fib: "},{"score":{"name":"fib_91lozjus6a5b_l1lcp73oc9te_temp","objective":"mcfp_runtime"}}]

# ASSIGN
scoreboard players set fib_91lozjus6a5b_l1lcp73oc9te_u41kmytd0iwn mcfp_runtime 1
scoreboard players operation fib_91lozjus6a5b_l1lcp73oc9te_nr3e651z7b8q mcfp_runtime = fib_91lozjus6a5b_n mcfp_runtime
scoreboard players operation fib_91lozjus6a5b_l1lcp73oc9te_nr3e651z7b8q mcfp_runtime += fib_91lozjus6a5b_l1lcp73oc9te_u41kmytd0iwn mcfp_runtime
scoreboard players reset fib_91lozjus6a5b_l1lcp73oc9te_u41kmytd0iwn mcfp_runtime
scoreboard players operation fib_91lozjus6a5b_n mcfp_runtime = fib_91lozjus6a5b_l1lcp73oc9te_nr3e651z7b8q mcfp_runtime
scoreboard players reset fib_91lozjus6a5b_l1lcp73oc9te_nr3e651z7b8q mcfp_runtime

# WHILE CONDITION
scoreboard players set fib_91lozjus6a5b_l1lcp73oc9te_0xouqicezd1w mcfp_runtime 25
scoreboard players set fib_91lozjus6a5b_l1lcp73oc9te_xr64ziewvzg2 mcfp_runtime 0
execute if score fib_91lozjus6a5b_n mcfp_runtime < fib_91lozjus6a5b_l1lcp73oc9te_0xouqicezd1w mcfp_runtime run scoreboard players set fib_91lozjus6a5b_l1lcp73oc9te_xr64ziewvzg2 mcfp_runtime 1
scoreboard players reset fib_91lozjus6a5b_l1lcp73oc9te_0xouqicezd1w mcfp_runtime

# WHILE REPEAT
execute if score should_break mcfp_runtime matches 1 run return 0
execute if score fib_91lozjus6a5b_l1lcp73oc9te_xr64ziewvzg2 mcfp_runtime matches 1 run execute if function mcfp:fib_91lozjus6a5b_l1lcp73oc9te run return 1
scoreboard players reset fib_91lozjus6a5b_l1lcp73oc9te_xr64ziewvzg2 mcfp_runtime

Language

Syntax

program        → declaration* EOF ;

declaration    → structDecl
               | funDecl
               | varDecl
               | statement ;

structDecl     → "struct" IDENTIFIER "{" varDecl* "}" ;
funDecl        → "func" function ;
varDecl        → "var" IDENTIFIER ( "=" expression )? ";" ;

statement      → exprStmt
               | forStmt
               | ifStmt
               | printStmt
               | returnStmt
               | whileStmt
               | importStmt
               | block ;

exprStmt       → expression ";" ;
forStmt        → "for" "(" ( varDecl | exprStmt | ";" )
                           expression? ";"
                           expression? ")" statement ;
ifStmt         → "if" "(" expression ")" statement
                 ( "else" statement )? ;
printStmt      → "print" expression ";" ;
returnStmt     → "return" expression? ";" ;
whileStmt      → "while" "(" expression ")" statement ;
importStmt     → "import" STRING ";" ;
block          → "{" declaration* "}" ;

expression     → assignment ;

assignment     → ( call "." )? IDENTIFIER "=" assignment
               | logic_or ;

logic_or       → logic_and ( "or" logic_and )* ;
logic_and      → equality ( "and" equality )* ;
equality       → comparison ( ( "!=" | "==" ) comparison )* ;
comparison     → term ( ( ">" | ">=" | "<" | "<=" ) term )* ;
term           → factor ( ( "-" | "+" ) factor )* ;
factor         → unary ( ( "/" | "*" ) unary )* ;

unary          → ( "!" | "-" ) unary | call ;
call           → primary ( "(" arguments? ")" | "." IDENTIFIER )* ;
primary        → "true" | "false" | NUMBER | IDENTIFIER
               | "(" expression ")" ;

function       → IDENTIFIER "(" parameters? ")" block ;
parameters     → IDENTIFIER ( "," IDENTIFIER )* ;
arguments      → expression ( "," expression )* ;

NUMBER         → DIGIT+ ;
STRING         → "\'" <any char except "\'">* "\'" ;
IDENTIFIER     → ALPHA ( ALPHA | DIGIT )* ;
ALPHA          → "a" ... "z" | "A" ... "Z" | "_" ;
DIGIT          → "0" ... "9" ;