Revision as of 11:28, 5 June 2012 by Lemming (basic definition)
A partial function is a function that is not defined for all possible arguments of the specified type. Examples in the Haskell standard library are:
tail: undefined for empty lists
(!!): undefined if the index is at least as big as the list length
div: undefined if the divisor is zero
The opposite is a total function.
There are methods to avoid the use of partial functions.