[Richard Suchenwirth] - This is part 3 of the series that began with [Playing APL] and [APLish] - a partial parser ''apl2t'' that converts a string in sub-APL to a string that can be eval'ed by Tcl (call ''apl''). It is partial in two ways: it does not attempt to build a complete parse tree, and it does not cover more than a tiny subset of APL, but some already: ---- % apl2t {N N rho 1,N rho 0} rho "$N $N" [, "1" [rho "$N" "0" ]] % set N 5 5 % apl {N N rho 1,N rho 0} 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 1 % apl N+2*0.5 6.414213562373095 Still a lot to do (quoted strings, compound operators like -:..), but it's tremendous fun...;-) namespace eval APL { namespace export apl apl2t proc apl s {uplevel [apl2t $s]} proc apl2t list { set res "" #---------- insert potential blanks everywhere, then reduce set list [join [split $list ""] \x81] foreach i {1 2} { regsub -all "(\[_A-Z0-9\])\x81(\[_A-Z0-9\])" $list {\1\2} list regsub -all "(\[a-z0-9\])\x81(\[a-z0-9\])" $list {\1\2} list } regsub -all "(\[.\])\x81(\[0-9\])" $list {\1\2} list regsub -all "(\[0-9\])\x81(\[.\])" $list {\1\2} list regsub -all \x81 $list " " list set op "" set last "" #---------- walk the list from back for {set n [llength $list]} {$n>0} {incr n -1} { set it [lindex $list [expr $n-1]] if [regexp {^[A-Z_]} $it] { if {$last!="val"} {set it $it\"} set res "\$$it $res" set last val } elseif {[regexp {^-?[0-9.]} $it]} { if {$last!="val"} {set it $it\"} set res "$it $res" set last val } elseif {$it==")"} { if {$last=="val"} {set res \"$res} set last embed set open [lsearch $list "("] if {$open<0} {error "unmatched paren"} set embed [lrange $list [incr open] [incr n -2]] set res "\[[apl2t $embed]\] $res" set n $open } else { if {$last=="val"} {set res \"$res} set last op if [llength $op] { set res "$op $res"; set op "" if {$n>2} {set res "\[$res\]"} } set op $it } } if {$last=="val"} {set res \"$res} if [llength $op] {set res "$op $res"} set res } } ---- [Arts and crafts of Tcl-Tk programming] - [Category String Processing]