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SortBy    --    sort a list


Syntax
SortBy(ref L: LIST, LessThanFunc: FUNCTION)

Description
This procedure sorts the elements of the list in L into increasing order with respect to the comparisons made by LessThanFunc ; it overwrites L and returns nothing.

The comparison function LessThanFunc takes two arguments and must return true if the first argument is less than the second, otherwise it must return false .

If you want to call SortBy(ref L,LessThanFunc) inside a function, and you have defined LessThanFunc at top level (rather than as an anonymous function), then you need to ensure that the name LessThanFunc is visible using TopLevel LessThanFunc;

Note that if both LessThanFunc(A, B) and LessThanFunc(B, A) return true , then A and B are viewed as being equal.

Example
/**/  Define LessThanLen(S, T)    -- define the sorting function
/**/    Return len(S) < len(T);
/**/  EndDefine;

/**/  L := ["bird", "mouse", "cat", "elephant"];
/**/  SortBy(ref L, LessThanLen);
/**/  L;
["cat", "bird", "mouse", "elephant"]

See Also