Agda- A dependently typed functional programming language and proof assistant

Safe HaskellNone




compileClauses Source


:: Maybe (QName, Type)

Translate record patterns and coverage check with given type?

-> [Clause] 
-> TCM CompiledClauses 

Process function clauses into case tree. This involves: 1. Coverage checking, generating a split tree. 2. Translation of lhs record patterns into rhs uses of projection. Update the split tree. 3. Generating a case tree from the split tree. Phases 1. and 2. are skipped if Nothing.

type Cls = [Cl] Source

nextSplit :: Cls -> Maybe (Bool, Int) Source

Get the index of the next argument we need to split on. This the number of the first pattern that does a match in the first clause.

properSplit :: Pattern -> Maybe Bool Source

Is is not a variable pattern? And if yes, is it a record pattern?

isVar :: Pattern -> Bool Source

Is this a variable pattern?

Maintain invariant: isVar = isNothing . properSplit!

splitOn :: Bool -> Int -> Cls -> Case Cls Source

splitOn single n cs will force expansion of catch-alls if single.

expandCatchAlls :: Bool -> Int -> Cls -> Cls Source

Expand catch-alls that appear before actual matches.


   true  y
   x     false
   false y

will expand the catch-all x to false.

Catch-alls need also to be expanded if they come before/after a record pattern, otherwise we get into trouble when we want to eliminate splits on records later.

Another example (see Issue 1650): f (x, (y, z)) true = a f _ false = b Split tree: 0 (first argument of f) - 1 (second component of the pair) - 3 (last argument of f) -- true -> a - false -> b We would like to get the following case tree: case 0 of _,_ -> case 1 of _,_ -> case 3 of true -> a; false -> b _ -> case 3 of true -> a; false -> b _ -> case 3 of true -> a; false -> b