Category:Initlib: Difference between revisions
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initlib.ps
<lang postscript>
%!PS
% conventions: parameter names with let begins with .
% basic definition, makes the definitions less verbose.
/. {bind def} bind def
/' {load} bind def
/reverse {{} exch {exch [3 1 roll aload pop]} forall}.
/let {dup length dict begin reverse {exch def} forall}.
/let* {reverse {exch def} forall}.
% some predicates.
/eq? {eq].
/list? {dup type /arraytype eq?}.
/leaf? {list? not}.
/empty? {dup length 0 eq?}.
/zero? {dup 0 eq?}.
% stacky functions
/rup {3 1 roll}.
/rdown {3 -1 roll}.
/# {exch dup rdown .makeoperator bind def} bind def
/getname {dup 0 get exch}.
/getbody {dup length 1 sub 1 exch getinterval}.
% convenience arithmetic
/+ {add}.
/- {sub}.
/* {mul}.
/\ {div}.
% lispy functions
/first {0 get}.
/car {first}.
Line 28 ⟶ 49:
/tail {dup length 1 sub get}.
/!tail {dup tail}.
/cons {[rup aload pop]
/tadd {[rup aload length 1 add -1 roll] }.
/uncons {getname getbody}.
/concat {exch [ rup aload pop counttomark -1 roll aload pop ] }.
% make a unit list.
/unit {1 array astore cvx}.
/succ {1 add}.
/pred {1 sub}.
/range {[rup exch aload pop rup exch rdown {} for]}.
% higher order thingies.
/map { [ rup forall ] }.
% [1 2 3 4] {1 add} map
/fold {rup exch rdown forall}.
%/reverse
% {} [1 2 3 4 5] {exch cons} forall
% [1 2 3 4] 0 {+} fold
% name - filter is taken so we are left with..
Line 52 ⟶ 75:
end}.
/zip {
dup length 0 eq rdown dup length 0 eq rdown or {exit} if
uncons rdown uncons rdown 4 2 roll unit cons rup exch
} loop pop pop
}.
% do on all elements of a tree.
/treemap {
[/.tree /.rec] let
/.tree '
{leaf?} /.rec '
{{empty?} {}
{dup
{first /.rec ' treemap} dip
{rest /.rec ' treemap} i cons}
ifte}
ifte
end}.
% control structures
% ift - allow stack invariant if condition
/ift {
4 dict begin
Line 70 ⟶ 107:
} ifelse
end}.
% ift - allow stack invariant ifelse condition
/ifte {
4 dict begin
Line 83 ⟶ 119:
} ifelse
end}.
% switch statement.
/is? {{exit} concat cvx ift}.
/cond {{exit} concat cvx loop}.
% combinators
/dip {
[/.v /.q] let
.q /.v '
end}.
/apply {exec}.
/i {cvx exec}.
/linrec {
{.rec1
{/.if ' /.then ' /.rec1 ' /.rec2 ' linrec} i
.rec2}
ifte
end}.
/binrec {
[/.if /.then /.rec1 /.rec2] let
/.if ' /.then '
{ .rec1
{/.if ' /.then ' /.rec1 ' /.rec2 ' binrec} dip
{/.if ' /.then ' /.rec1 ' /.rec2 ' binrec} i
.rec2 }
ifte
end}.
/genrec {
[/.if /.then /.rec1 /.rec2] let
/.if ' /.then '
{.rec1
{/.if ' /.then ' /.rec1 ' /.rec2 ' genrec}
.rec2}
ifte
end}.
/tailrec {{} linrec}.
/primrec {
5 dict begin
/lzero? {
{list?} {empty?}
{zero?}
ifte}.
/lnext {
{list?} {rest}
{pred}
ifte}.
[/.param /.then /.rec] let*
{/.param ' lzero?} /.then '
{.param
{/.param ' lnext /.then ' /.rec ' primrec} i
.rec}
ifte
end}.
% debug
/puts {= (\n) print flush}.
/, {(=============\n)
print pstack
(=============\n) print}.
% set the prompt to something else so that we know initlib is loaded.
/prompt {(>| ) print flush} bind def
</lang>
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