Grammar Reference¶

MOL uses an LALR(1) grammar parsed by Lark. The full grammar is in mol/grammar.lark.

EBNF Grammar¶

Program Structure¶

program : statement+

statement : show_stmt
          | declare_stmt
          | assign_stmt
          | if_stmt
          | while_stmt
          | for_stmt
          | func_def
          | return_stmt
          | trigger_stmt
          | link_stmt
          | process_stmt
          | access_stmt
          | sync_stmt
          | evolve_stmt
          | emit_stmt
          | listen_stmt
          | block_stmt
          | guard_stmt
          | pipeline_def
          | expr_stmt

Statements¶

show_stmt     : "show" expr
declare_stmt  : "let" NAME "be" expr
              | "let" NAME ":" TYPE "be" expr
assign_stmt   : "set" NAME "to" expr
if_stmt       : "if" expr "then" block elif* else? "end"
while_stmt    : "while" expr "do" block "end"
for_stmt      : "for" NAME "in" expr "do" block "end"
func_def      : "define" NAME "(" params? ")" block "end"
return_stmt   : "return" expr?
guard_stmt    : "guard" expr
              | "guard" expr ":" expr
pipeline_def  : "pipeline" NAME "(" params? ")" block "end"

Expressions (by precedence, low → high)¶

expr         : pipe_chain
pipe_chain   : or_expr ("|>" or_expr)*
or_expr      : and_expr ("or" and_expr)*
and_expr     : not_expr ("and" not_expr)*
not_expr     : "not" not_expr | comparison
comparison   : addition (comp_op addition)*
addition     : multiply (("+"|"-") multiply)*
multiply     : unary (("*"|"/"|"%") unary)*
unary        : "-" unary | power
power        : atom ("^" unary)?

Atoms¶

atom : NUMBER
     | ESCAPED_STRING
     | "true" | "false" | "null"
     | "[" (expr ("," expr)*)? "]"          -- list
     | "{" (pair ("," pair)*)? "}"          -- map
     | NAME "(" (expr ("," expr)*)? ")"     -- function call
     | atom "." NAME "(" (expr ("," expr)*)? ")"  -- method call
     | atom "." NAME                        -- field access
     | atom "[" expr "]"                    -- index access
     | NAME                                -- variable reference
     | "(" expr ")"                        -- grouping

Type Names¶

TYPE : "Thought" | "Memory" | "Node" | "Stream"
     | "Number" | "Text" | "Bool" | "List"
     | NAME

Lexical Rules¶

Comments¶

-- This is a comment (to end of line)

Identifiers¶

Names must start with a letter or underscore, followed by letters, digits, or underscores.

Keywords (30)¶

if then elif else end while for in do define return begin
let be set to show and or not is true false null
trigger link process access sync evolve emit listen with
pipeline guard

Operators¶

|>  +  -  *  /  %  ^
==  !=  >  <  >=  <=  is  is not
and  or  not

Literals¶

Numbers:  42  3.14  -17  0.001
Strings:  "hello"  "multi\nline"  "with \"escapes\""
Booleans: true  false
Null:     null