(types.ps) run
(reader.ps) run

% read
/READ {
    /str exch def
    str read_str
} def


% eval
/EVAL { 2 dict begin
    % just "return" the "ast"
    /env exch def
    /ast exch def
    ast
end } def


% print
/PRINT {
    true _pr_str
} def


% repl
/REP { READ (stub env) EVAL PRINT } def

/stdin (%stdin) (r) file def 

{ % loop
    (user> ) print flush

    stdin 99 string readline

    not { exit } if  % exit if EOF

    %(\ngot line: ) print dup print (\n) print flush

    { %try
        REP print (\n) print
    } stopped {
        (Error: ) print
        get_error_data false _pr_str print (\n) print
        clear
    } if
} bind loop

(\n) print  % final newline before exit for cleanliness
quit