Generation of Flambda intermediate language code from Lambda code by performing a form of closure conversion.

Function declarations (which may bind one or more variables identifying functions, possibly with mutual recursion) are transformed to Set_of_closures expressions. Project_closure expressions are then used to select a closure for a particular function from a Set_of_closures expression. The Set_of_closures expressions say nothing about the actual runtime layout of the closures; this is handled when Flambda code is translated to Clambda code.

The following transformations are also performed during closure conversion:

• Constant blocks (by which is meant things wrapped in Lambda.Const_block) are converted to applications of the Pmakeblock primitive.
• Levent debugging event nodes are removed and the information within them attached to function, method and raise calls.
• Tuplified functions are converted to curried functions and a stub function emitted to call the curried version. For example: let rec f (x, y) = f (x + 1, y + 1) is transformed to: let rec internal_f x y = f (x + 1,y + 1) and f (x, y) = internal_f x y (* f is marked as a stub function *)
• The Pdirapply and Prevapply application primitives are removed and converted to normal Flambda application nodes.

The lambda_to_flambda function is not re-entrant.