phone-numbers.tcl

#!/bin/tclsh

array set alnum {
	2	abc
	3	def
	4	ghi
	5	jkl
	6	mno
	7	pqrs
	8	tuv
	9	wxyz
}

set numbers [split [lindex $argv 0] {}]
set letters [lmap n $numbers {split [lindex [array get alnum $n] 1] ""}]

proc letterMap {x y} {
	return [lmap a $x {lmap b $y {string cat $a $b}}]
}

proc phoneLetters {letterList} {
	if {[llength $letterList] < 2} {return [join $letterList]}
	return [phoneLetters [list [join [letterMap {*}[lrange $letterList 0 1]]] {*}[lrange $letterList 2 end]]]
}

puts [phoneLetters $letters]