retroforth/doc/Hyperstatic.md
crc ed89e0bde8 rename references to old names in doc
FossilOrigin-Name: 0b0cd20ed69027a7d9b5f2d905d7b9e033e2976208385652d888da35432a4482
2018-05-07 16:39:49 +00:00

31 lines
870 B
Markdown

# Hyperstatic Global Environment
This now brings up an interesting subpoint. Retro provides a *hyper-
static global environment.* This can be difficult to explain, so let's
take a quick look at how it works:
~~~
#1000 'a var<n>
:scale (x-y) @a * ;
#3 scale n:put
>>> 3000
#100 !a
#3 scale n:put
>>> 300
#5 'a var<n>
#3 scale n:put
>>> 300
@a n:put
>>> 5
~~~
Output is marked with **\>\>\>**.
Note that we create two variables with the same name (*a*). The definition
for `scale` still refers to the old variable, even though we can no longer
directly manipulate it.
In a hyper-static global environment, functions continue to refer to the
variables and earlier functions that existed when they were defined. If
you create a new variable or function with the same name as an existing
one, it only affects future code.