>> help reword
USAGE:
        REWORD source values /case /only /escape char /into output

DESCRIPTION:
        Make a string or binary based on a template and substitution values.
        REWORD is a function value.

ARGUMENTS:
        source -- Template series with escape sequences (any-string! binary!)
        values -- Keyword literals and value expressions (map! object! block!)

REFINEMENTS:
        /case -- Characters are case-sensitive
        /only -- Use values as-is, do not reduce the block, insert block values
        /escape -- Choose your own escape char(s) or [begin end] delimiters
                char -- Default "$" (char! any-string! binary! block! none!)
        /into -- Insert into a buffer instead (returns position after insert)
                output -- The buffer series (modified) (any-string! binary!)

>> reword/escape "ba" [a 1 b 2] none
== "21"  ; /escape none like /escape ""

>> reword "$a$A$a" [a 1 A 2]
== "222"  ; case-insensitive, last value wins
>> reword/case "$a$A$a" [a 1 A 2]
== "121"  ; case-sensitive, even with words

>> reword/escape "!bang;" [bang "!"] ["!" ";"]  ; not using a real XML entity because of CC, so pretend they use ! instead
== "!"  ; Leading and trailing delimiters considered
>> reword/escape "!bang;bang;" [bang "!"] ["!" ";"]
== "!bang;"  ; One-pass, continues after the replacement
>> reword/escape "!bang;bang;" [bang "!"] ["!"]
== "!;bang;"  ; No trailing delimiter specified

>> reword "$a" ["a" ["A" "B" "C"]]
== "C"  ; evaluate a block value as code by default
>> reword/only "$a" ["a" ["A" "B" "C"]]
== "ABC"  ; Just insert a block value with /only

>> reword "$a$b$+" [a 1 + 1 b 2 + 2]
== "24$+"  ; Value expressions evaluated, keys treated as literals
>> reword/only "$a$b$+" [a 1 + 1 b 2 + 2]
== "122"   ; With /only, treated as raw values, + keyword defined twice in this case
>> reword "$a ($b)" ["a" does ["AAA"] "b" ()]
== "AAA ($b)"  ; Evaluates function builders and parens too. Note that b was undefined because () evaluates to unset
>> reword/only "$a ($b)" reduce ["a" does ["AAA"] "b" ["B" "B" "B"]]
== "AAA (BBB)"  ; With /only of explicitly reduced spec, functions still called even though blocks are just inserted

>> reword "$a" [a: 1]
== "1"  ; It should be easy to switch from block to object specs
>> reword "$a" context [a: 1]
== "1"  ; ... like this, so we should special-case set-words
>> reword "$a" ['a 1]
== "1"  ; It should be easy to explicitly reduce the same spec
>> reword "$a" reduce ['a 1]
== "1"  ; ... like this, so we should special-case lit-words
>> reword/escape "a :a /a #a" [a 1 :a 2 /a 3 #a 4] none
== "1 2 3 4"  ; But otherwise let word types be distinct

>> reword to-binary "$a$A$a" [a 1 A 2]
== #{010201}  ; binaries supported, note the case-sensitivity, same key rules, values inserted by binary rules
>> tail? reword/into to-binary "$a$A$a" [a 1 A 2] #{}
== true  ; /into option behaves the same
>> head reword/into "$a$A$a" [a 1 A 2] #{}
== #{020202}  ; string templates can insert into binaries, note the case-insensitivity
>> head reword/case/into "$a$A$a" [a 1 A 2] #{}
== #{010201}  ; ... and this time it's case-sensitive
>> head reword/into to-binary "b$a$A$ac" [a 1 A 2] ""
== "b121c"  ; Binary templates can insert into strings, using string insert rules, still case-sensitive

>> reword/escape <a href="http://blah/blah?a!b" /> ["!" "!bang;"] none
== <a href="http://blah/blah?a!bang;b" />  ; Yes, tag source should work too
>> head reword/escape/into {a href="http://blah/blah?a!b" /} ["!" "!bang;"] none to-tag ""
== <a href="http://blah/blah?a!bang;b" />  ; ... and output as well