diff options
Diffstat (limited to 'src/algebra')
| -rw-r--r-- | src/algebra/stream.spad.pamphlet | 32 |
1 files changed, 17 insertions, 15 deletions
diff --git a/src/algebra/stream.spad.pamphlet b/src/algebra/stream.spad.pamphlet index 8be08ff7..b7fe4421 100644 --- a/src/algebra/stream.spad.pamphlet +++ b/src/algebra/stream.spad.pamphlet @@ -649,20 +649,22 @@ Stream(S): Exports == Implementation where --% representation - -- The Rep is a pair of one of three forms: - -- [value: S, rest: %] - -- [nullstream: Magic, NIL ] - -- [nonnullstream: Magic, fun: () -> %] + -- The Rep is a pair of one of three kinds: + -- [value: S, rest: %] + -- [%nullStream: Magic, %nil ] + -- [%nonNullStream: Magic, fun: () -> %] -- Could use a record of unions if we could guarantee no tags. - macro NullStream == _$NullStream$Foreign(Builtin) - macro NonNullStream == _$NonNullStream$Foreign(Builtin) + import %nil: % from Foreign Builtin -- to indicate nil stream + import %nullStream: S from Foreign Builtin -- end-of-stream token + import %nonNullStream: S from Foreign Builtin -- plentyfull stream token - import %head: % -> S from Foreign Builtin - import %tail: % -> % from Foreign Builtin + import %head: % -> S from Foreign Builtin + import %tail: % -> % from Foreign Builtin + import %pair: (S,%) -> % from Foreign Builtin - explicitlyEmpty? x == %peq(frst x,NullStream)$Foreign(Builtin) - lazy? x == %peq(frst x,NonNullStream)$Foreign(Builtin) + explicitlyEmpty? x == %peq(frst x,%nullStream)$Foreign(Builtin) + lazy? x == %peq(frst x,%nonNullStream)$Foreign(Builtin) --% signatures of local functions @@ -683,8 +685,8 @@ Stream(S): Exports == Implementation where -- destructively changes x to a null stream setToNil!(x: %): % == - setfrst!(x,NullStream) - setrst!(x,%nil$Foreign(Builtin)) + setfrst!(x,%nullStream) + setrst!(x,%nil) x --% SETCAT functions @@ -914,7 +916,7 @@ Stream(S): Exports == Implementation where --% RCAGG functions empty() == - %pair(NullStream,%nil$Foreign(Builtin))$Foreign(Builtin) + %pair(%nullStream,%nil) lazyEval(x: %): % == (rst(x):(()-> %)) () @@ -949,7 +951,7 @@ Stream(S): Exports == Implementation where (concat(frst x, first(rst x,(n-1) :: NNI))) concat(s:S,x:%) == - %pair(s,x)$Foreign(Builtin) + %pair(s,x) cons(s,x) == concat(s,x) @@ -1070,7 +1072,7 @@ Stream(S): Exports == Implementation where [true, npp, periode] delay(fs:()->%) == - %pair(NonNullStream,fs)$Foreign(Builtin) + %pair(%nonNullStream,fs : %) explicitEntries? x == not explicitlyEmpty? x and not lazy? x |