:: Bool -> a -> a -> a

if-then-else as function. Example:

if' (even n) "even" $
if' (isPrime n) "prime" $
"boring"

The same as if', but the name is chosen such that it can be used for GHC-7.0's rebindable if-then-else syntax.

for support of if .. then .. else

RebindableSyntax splats this, and I'm not sure where it exists in GHC land

Because of RebindableSyntax, this is necessary to enable you to use if-then-else expressions. No need to call it directly.

Definition of ifThenElse for use with RebindableSyntax

This is the if-then-else operator, With it you can write xxx ? yyy $ zzz instead of if xxx then yyy else zzz. Following may or may not be cleaner to you ; )

isFoo <- checkFoo
isFoo ? foo
$ bar

Hang on the True case of bool.

onTrue b f t = bool f t b

Hang on the False case of bool.

onFalse b t f = bool f t b

Same as bool, except the Bool comes before the case functions. Equivalent type signature:

boolL :: forall r. Analysis Bool r

The implementation is just:

boolL = gcase

A simple conditional operator

Fold left for n-ary tuples

>>> foldlT (-) 0 (4,3,2,1)
-10

Fold right for n-ary tuples

>>> foldrT (-) 0 (4,3,2,1)
2

balanceL p l r returns a balanced tree for the sequence l ++ [p] ++ r. It assumes that l and r are close to being balanced, and that only l may contain too many elements.