Prelude> map (1+) [1..10] [2, 3, 4, 5, 6, 7, 8, 9, 10, 11] Prelude> filter even $$ [2, 4, 6, 8, 10] Prelude>A -r<str> option can be used to change the repeat string---the symbol used to recall the last expression---to <str>. For example, users of Standard ML might be more comfortable using:
Prelude> :set -rit Prelude> 6 * 7 42 Prelude> it + it 84 Prelude>Another reason to change the repeat string is to avoid clashes with uses of the same symbol in a particular program; for example, if $$ is defined as an operator in a program.
Note that the repeat string must be a valid Haskell identifier or symbol, although it will always be parsed as an identifier. If the repeat string is set to a value that is neither an identifier or symbol (for example, -r0), then the repeat last expression facility will be disabled.