diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/execution.md | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/doc/execution.md b/doc/execution.md index bf0d524..377434d 100644 --- a/doc/execution.md +++ b/doc/execution.md @@ -206,3 +206,52 @@ epic as it should be.) Execution of and with scopes ---------------------------- +Most global functions can be applied to scopes. When this happens a corresponding member of the scope is resolved instead. +Usually this member takes the form `#name` for a global function `name`. If the scope is not the first argument to a function +(but the first scope argument), then the resulting member name is something like `#-021 name` where the digits give the +stack manipulation of `-` which would be necessary to put the object back to the correct stack position. + + + < + { 5 } "#len" deff + > len dump + 0000000000000005 + < + { 5 add } "#add" deff + > ==s + 2 s add dump + 0000000000000007 + < + { _ add } "#*" deff + > ==s + 2 s * dump + 0000000000000004 + < + { 2 add } "#-01 add" deff + > 5 add dump + 0000000000000007 + +The member function `#*` is used whenever an execution of the scope would be required. + + +To correctly handle the application of a typed function to a scope representing a container data +type, a few more members are needed. At least these are +* `#*` - to read elements of the container +* `#=[]` - to write elements of the container +* `#in` - to determine the input type of the scope, will usually just be `{ [ 0 ] }` +* `#out` - to determine the output type of the scope, will usually just be `{ [ 0 ] }` +But usually, the container will have a finite domain, and a new container needs to be constructed +for the result. This is handled by +* `#each` - applies a function to each of the containers values +* `#dom` - returns the concrete, finite domain +* `#istart` - returns an object to iterate over the container contents, pointing to the first, usually an integer +* `#istep` - takes such an iterator object and points it to the next container element +* `#iend` - takes an iterator object and returns non-zero if it points after the last element, i.e. the end of the container has been reached +* `#itrans` - takes an iterator object and transforms it into an element of the container's domain. This will often be the identity function. +* `#iclone` - creates a new container object which can assing via `=[]` elements for the entire original domain. + +See elymas/lib/map.ey for an example. + + +(FIXME: Scopes will also be able to define member functions `#.`, `#.|`, `#.?` and `#.=` to handle references to non-existing name slots. +This does not yet work correctly with the optimizer.) |