String search and replace

ssr[x;y;z]

Where

• x is a string
• y is a pattern as a string (no asterisk)
• z is a string or a function

returns x with each substring matching y replaced by:

• z if z is a string
• z[Y] where z is a function and Y is the matched substring

q)s:"toronto ontario"
q)ssr[s;"ont";"x"]      / replace "ont" by "x"
"torxo xario"
q)ssr[s;"t?r";upper]    / replace matches by their uppercase
"TORonto onTARio"