diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/docs/backend/rts.md | 25 |
1 files changed, 12 insertions, 13 deletions
diff --git a/doc/docs/backend/rts.md b/doc/docs/backend/rts.md index d401f3a..36de2ce 100644 --- a/doc/docs/backend/rts.md +++ b/doc/docs/backend/rts.md @@ -53,19 +53,18 @@ The arguments of some built-in constructors can be unboxed: ### Hnf descriptors Descriptors of hnf nodes are located in the data section. They contain -information about the arity of the node. It also contains the number of -arguments to be curried in, which is 0 for all data constructors but non-zero -for the [descriptors of closures](#closure-descriptors). (This means that, in -principle, data constructor descriptors only need a halfword.) +information about the arity of the node. ```mipsasm .align 1 __main_cTuple: .byte 2 # pointer arity .byte 0 # basic value arity - .byte 0 # number of arguments to be curried in ``` +NB: [descriptors of closures](#closure-descriptors) also contain the number of +arguments to be curried in (minus 1). + ### Thunk descriptors Thunk nodes point to the code that can evaluate them. Above this code a descriptor is used storing information about arity and strictness: @@ -78,13 +77,13 @@ __main_nappend: # ... ``` -!!! warning "Implementation may change" - Strictness will probably be removed in the future, as evaluating arguments - will be moved out of the driver into generated code (see - [evaluation](#evaluation)). +!!! warning "Implementation will change" + Strictness will be removed in the future, as evaluating arguments will be + moved out of the driver into generated code (see [evaluation](#evaluation)). - This also makes the implementation of `ap` simpler, as it does not need to - check strictness of the function it evaluates any more. + This makes the implementation of `ap` simpler, as it does not need to check + strictness of the function it evaluates any more. Currently `ap` assumes all + arguments are strict. ### Closure descriptors For each thunk with a non-zero number of arguments there is also a closure @@ -97,12 +96,12 @@ this: # entry for closure with 0 arguments: .byte 0 # pointer arity .byte 0 # basic value arity - .byte 2 # number of arguments that are still to be curried in + .byte 1 # number of arguments that are still to be curried in minus 1 .byte 0 # reserved # entry for closure with 1 argument: .byte 1 # pointer arity .byte 0 # basic value arity - .byte 1 # number of arguments that are still to be curried in + .byte 0 # number of arguments that are still to be curried in minus 1 .byte 0 # reserved # pointer to corresponding code entry: __main_uappend: |