Am Montag, 2. März 2009 20:42 schrieb 7stud:
mySort xs = let myCompare x y
| lx < ly = LT | lx == ly = EQ | lx > ly = GT
where lx = length x ly = length y in sortBy myCompare xs
Prelude> :load bhask.hs [1 of 1] Compiling Main ( bhask.hs, interpreted )
bhask.hs:4:16: parse error (possibly incorrect indentation) Failed, modules loaded: none. Prelude>
Line 4 is the first guard.
That line must be indented further than the first letter of myCompare in the line above. After the keyword 'let', the position of the start of the next significant token (not whitespace or comments), sets a new indentation level. The definiton begun there extends until - a line indented less or equally far is encountered - the keyword 'in' appears - an explicit semicolon ends the definition If a line indented less appears before the keyword 'in', a parse error results. Details can be found in http://haskell.org/onlinereport/syntax-iso.html#sect9.3