Shane's Turing complete language

# See https://www.reddit.com/r/ProgrammingLanguages/comments/d076go/how_to_write_a_turingcomplete_programming/ezaqcs2

grammar Shane's-Turing-complete-language {

rule TOP { <.ws> <stmts> }

rule stmts { <expr>+ }

rule expr { <ifExpr> | <whileExpr> | <opExpr> | <storeSet> | <storeGet> | <value> }

rule ifExpr { 'if' <stmts> 'then' <stmts> [ 'else' <stmts> ]? 'end' }

rule whileExpr { 'while' <stmts> 'do' <stmts> 'end' }

rule storeSet { [ '[' <stmts> ']' | <var> ] '=' <expr> }

rule storeGet { '[' <stmts> ']' | <var> }

my @keywords = < if then else while do end >;

token var { :i <!before @keywords> <[_a..z]> \w* }

my @ops = << <= >= == - + * / < > >>;

token op { @ops }

rule opExpr { <op> <expr> <expr> }

token value { '-'? <[0..9]>+ }

}

given Shane's-Turing-complete-language.parse: slurp 'sieve-code' { .Str.say for .<stmts><expr> }