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Up to [Research Unix] / researchv10dc / cmd / icon / tests|
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1.1 root 1: procedure Gk(k)
2: local i, m_
3: i := 0
4: m_ := table(0)
5:
6: suspend m_[C_([i +:= |1,k])] := i - m_[C_([m_[C_([i - k,k])],k])]
7: end
8: procedure Q()
9: local i, m_
10: i := 0
11: m_ := table(0)
12: suspend m_[i +:= 1] := 1
13: suspend m_[i +:= 1] := 1
14: suspend m_[i +:= |1] := m_[i - m_[i - 1]] + m_[i - m_[i - 2]]
15: end
16: procedure Fib()
17: local i, m_
18: i := 0
19: m_ := table(0)
20: suspend m_[i +:= 1] := 1
21: suspend m_[i +:= 1] := 1
22: suspend m_[i +:= |1] := m_[i - 1] + m_[i - 2]
23: end
24: procedure G()
25: local i, m_
26: i := 0
27: m_ := table(0)
28:
29: suspend m_[i +:= |1] := i - m_[m_[i - 1]]
30: end
31: procedure Fibs()
32: local i, m_
33: i := 0
34: m_ := table("")
35: suspend m_[i +:= 1] := "a"
36: suspend m_[i +:= 1] := "b"
37: suspend m_[i +:= |1] := m_[i - 1] || m_[i - 2]
38: end
39: procedure Unop_(op,X) # op(X)
40: local e, a, i, s
41: if S_(X) then {
42: a := copy(X.a)
43: i := *X.a
44: e := create !a | Pre_(X.e,i)
45: return Sequence([],create |Unop_(op,@e))
46: }
47: else suspend op(X)
48: end
49:
50: procedure Binop_(op,X1,X2) # op(X1,X2)
51: local e1, e2, a1, a2, i1, i2, s1, s2
52: if not S_(X1 | X2) then suspend op(X1,X2)
53: else {
54: s1 := Seq_(X1)
55: s2 := Seq_(X2)
56: a1 := copy(s1.a)
57: a2 := copy(s2.a)
58: i1 := *s1.a
59: i2 := *s2.a
60: e1 := create !a1 | Pre_(s1.e,i1)
61: e2 := create !a2 | Pre_(s2.e,i2)
62: return Sequence([],create |Binop_(op,@e1,@e2))
63: }
64: end
65:
66: procedure Triop_(op,X1,X2,X3) # op(X1,X2,X2)
67: local e1, e2, e3, a1, a2, a3, i1, i2, i3, s1, s2, s3
68: if not S_(X1 | X2 | X3) then suspend op(X1,X2,X3)
69: else {
70: s1 := Seq_(X1)
71: s2 := Seq_(X2)
72: s3 := Seq_(X3)
73: a1 := copy(s1.a)
74: a2 := copy(s2.a)
75: a3 := copy(s3.a)
76: i1 := *s1.a
77: i2 := *s2.a
78: i3 := *s3.a
79: e1 := create !a1 | Pre_(s1.e,i1)
80: e2 := create !a2 | Pre_(s2.e,i2)
81: e3 := create !a3 | Pre_(s3.e,i3)
82: return Sequence([],create |Triop_(op,@e1,@e2,@e3))
83: }
84: end
85:
86: procedure Quadop_(op,X1,X2,X3,X4) # op(X1,X2,X3,X4)
87: local e1, e2, e3, e4, a1, a2, a3, a4, i1, i2, i3, i4, s1, s2, s3, s4
88: if not S_(X1 | X2 | X3 | X4) then suspend op(X1,X2,X3,X4)
89: else {
90: s1 := Seq_(X1)
91: s2 := Seq_(X2)
92: s3 := Seq_(X3)
93: s4 := Seq_(X4)
94: a1 := copy(s1.a)
95: a2 := copy(s2.a)
96: a3 := copy(s3.a)
97: a4 := copy(s4.a)
98: i1 := *s1.a
99: i2 := *s2.a
100: i3 := *s3.a
101: i4 := *s4.a
102: e1 := create !a1 | Pre_(s1.e,i1)
103: e2 := create !a2 | Pre_(s2.e,i2)
104: e3 := create !a3 | Pre_(s3.e,i3)
105: e4 := create !a4 | Pre_(s4.e,i4)
106: return Sequence([],create |Quadop_(op,@e1,@e2,@e3,@e4))
107: }
108: end
109:
110: procedure P_(a) # limited evaluation
111: return case *a of {
112: 2 : Unop_(a[1],a[2])
113: 3 : Binop_(a[1],a[2],a[3])
114: 4 : Triop_(a[1],a[2],a[3],a[4])
115: 5 : Quadop_(a[1],a[2],a[3],a[4],a[5])
116: default : stop("Too many arguments in parallel evaluation")
117: }
118: end
119:
120: record Sequence(a,e) # sequence data type
121: record Undef() # for unique "undefined" value
122:
123: global Phi, Iplus, Iplus_, Izero, Undef_, X_, Genseq_, GenJ_
124:
125: procedure At(X) # element generation for sequences
126: every i := seq() do
127: if s := Ref_(X,i) then suspend s
128: else fail
129: end
130:
131: procedure C_(a) # identifying "subscript" for
132: local s # recurrence lookup
133: s := a[1]
134: every s ||:= "." || image(a[2 to *a])
135: return s
136: end
137:
138: procedure Cat_(X1,X2) # concatenation of X1 and X2
139: local s1, s2, e1, e2, i1, i2, a1, a2
140: s1 := Seq_(X1)
141: s2 := Seq_(X2)
142: e1 := s1.e
143: i1 := *s1.a
144: e2 := s2.e
145: i2 := *s2.a
146: a2 := copy(s2.a)
147: return Sequence(copy(s1.a),create Pre_(e1,i1) | !a2 | Pre_(e2,i2))
148: end
149:
150: procedure Collapse_(X) # generate scalars from X
151: if S_(X) then
152: suspend Collapse_(Gen_(X))
153: else return X
154: end
155:
156: procedure Expr_(X) # return refreshed co-expression for X
157: if type(X) == "Sequence" then return ^X.e | &null
158: else if /X then return Phi.e
159: else return create X
160: end
161:
162: procedure Gen_(X,v) # generate elements of X
163: local i, x
164: if X_[\v] === Undef_ then fail # termination heuristic
165: if not S_(X) then return X # note: does not fail if X null-valued
166: every i := seq() do {
167: if x := X.a[i] then # produce stored values first
168: suspend x
169: else { # transfer remaining values
170: put(X.a,@X.e) | fail
171: if x := X.a[i] then suspend x else fail
172: }
173: if X_[\v] === Undef_ then fail # termination heuristic
174: }
175: end
176:
177: procedure Generic_(p,X) # apply p to X
178: if /X then fail
179: return if S_(X) then every p(Gen_(X)) else p(X)
180: end
181:
182: procedure Init_()
183: GenJ_ := Gen_
184: Undef_ := Undef()
185: X_ := table()
186: Iplus := Sequence([],create seq(1))
187: Iplus_ := Sequence([],create seq(1))
188: Izero := Sequence([],create seq(0))
189: Izero_ := Sequence([],create seq(0))
190: Phi := Sequence([], create &fail)
191: Genseq_ := Iplus_
192: end
193:
194: procedure Lim_(X,i) # limit X to i elements
195: local e, s, a, n
196:
197: if i < 1 then return .Phi
198: s := Seq_(X)
199: a := copy(s.a)
200: n := *s.a
201: return Sequence([],create (!a | Pre_(s.e,n)) \ i)
202:
203: end
204:
205: procedure Post_(e,i) # limit X to at most i values
206: e := ^e
207: suspend |@e \ i
208: end
209:
210: procedure Pp_(v) # push/pop undefined marker
211: X_[\v] := &null
212: suspend
213: X_[\v] := &null
214: fail
215: end
216:
217: procedure Pre_(e,i) # skip first i values of X
218: e := ^e
219: every 1 to i
220: do @e | fail
221: suspend |@e
222: end
223:
224: procedure Qq_(v) # pop/push undefined marker
225: X_[\v] := &null
226: suspend
227: X_[\v] := &null
228: fail
229: end
230:
231: procedure Red_(X,op) # reduction of X over op
232: local x, y, i
233: i := 1
234: suspend x := Ref_(X,i)
235: while y := Ref_(X,i +:= 1) do
236: suspend (x := op(x,y)) # op(x,y) may fail, not changing x
237: end
238:
239: procedure Ref_(X,i,v) # X!i
240: local x
241: if i < 1 then {
242: X_[\v] := Undef_ # termination heuristic
243: fail
244: }
245: if not S_(X) then # J: coerce to a sequence
246: X := Sequence([],create X)
247: if i > *X.a then
248: every 1 to i - *X.a do
249: put(X.a,@X.e) | {
250: X_[\v] := Undef_ # termination heuristic
251: fail
252: }
253: return X.a[i] # note that this is not dereffed
254: end
255:
256: procedure S_(x) # is X a sequence?
257: return type(x) == "Sequence"
258: end
259:
260: procedure Seq_(X) # coerce X to a unit sequence
261: if type(X) == "Sequence" then return X
262: else if /X then return Phi
263: else return Sequence([],create X)
264: end
265:
266: procedure Shift_(X,i) # shift X left by i elements
267: local e,a,n,s
268: if i < 1 then return .Phi
269: s := Seq_(X)
270: a := copy(s.a)
271: n := *a
272: if n > i then {
273: e := create a[i+1 to n] | Pre_(s.e,n)
274: return Sequence([],create |@e)
275: }
276: else
277: return Sequence([], create Pre_(s.e,i))
278: end
279: global Fibseq, Abc, U, L
280: procedure main();
281: Init_()
282: Abc := Sequence([], create ("") | ("a") | ("b") | ("c") | ("aa") | ("ab") | ("ac") | ("ba") | ("bb") | ("bc") | ("ca") | ("cb") | ("cc") | ("aaa"));
283: Fibseq := Sequence([], create (Fib()));
284: U := Sequence([], create ("A") | ("B") | ("C"));
285: L := Sequence([], create ("a") | ("b"));
286: sec1();
287: sec1();
288: sec1();
289: sec2_0();
290: sec2_0();
291: sec2_0();
292: sec2_1();
293: sec2_1();
294: sec2_1();
295: sec2_3();
296: sec2_3();
297: sec2_3();
298: sec2_4();
299: sec2_4();
300: sec2_4();
301: sec3_1();
302: sec3_1();
303: sec3_1();
304: sec3_2();
305: sec3_2();
306: sec3_2();
307: sec3_3();
308: sec3_3();
309: sec3_3();
310: sec4();
311: sec4();
312: sec4();
313: sec5();
314: sec5();
315: sec5();
316: end
317: procedure sec1();
318: write("{x, {y}}: ",Image(Sequence([], create ("x") | (Sequence([], create ("y"))))));
319: write("|{{1,2}}|: ",Length(Sequence([], create (Sequence([], create (1) | (2))))));
320: write("F!6: ",Ref_((Fibseq),6,));
321: write("{1,2,3} -> {6,7,8,9}: ",Image(Cat_((Sequence([], create (1) | (2) | (3))),(Sequence([], create (6) | (7) | (8) | (9)))),10));
322: write("F sub 3:5: ",Image(Subseq(Fibseq,3,5)));
323: write("F sub 5:inf: ",Image(Shift_((Fibseq),4)));
324: end
325: procedure sec2_0();
326: write("Fibonacci sequence: ",Image(Fibseq,10));
327: write("closure of a,b,c: ",Image(Abc,10));
328: write("[i]: ",Image(Sequence([],create (Pp_("i") &
329: i := Gen_(Genseq_,"i") & 1(GenJ_((i) ,"i"),Qq_("i"))))));
330: write("[i - 1]: ",Image(Sequence([],create (Pp_("i") &
331: i := Gen_(Genseq_,"i") & 1(GenJ_((Binop_("-",i,1)) ,"i"),Qq_("i"))))));
332: write("[i ^ 2]: ",Image(Sequence([],create (Pp_("i") &
333: i := Gen_(Genseq_,"i") & 1(GenJ_((Binop_("^",i,2)) ,"i"),Qq_("i"))))));
334: write("[i mod 3]: ",Image(Sequence([],create (Pp_("i") &
335: i := Gen_(Genseq_,"i") & 1(GenJ_((Binop_("%",i,3)) ,"i"),Qq_("i"))))));
336: write("[a to i]: ",Image(Sequence([],create (Pp_("i") &
337: i := Gen_(Genseq_,"i") & 1(GenJ_((repl("a",i)) ,"i"),Qq_("i"))))));
338: write("[1]: ",Image(Sequence([],create (Pp_("i") &
339: i := Gen_(Genseq_,"i") & 1(GenJ_((1) ,"i"),Qq_("i"))))));
340: write("[aa]: ",Image(Sequence([],create (Pp_("i") &
341: i := Gen_(Genseq_,"i") & 1(GenJ_(("aa") ,"i"),Qq_("i"))))));
342: end
343: procedure sec2_1();
344: write("[Iplus:i]: ",Image(Sequence([],create (Pp_("i") &
345: i := Gen_(.Iplus,"i") & 1(GenJ_((i) ,"i"),Qq_("i"))))));
346: write("[Izero:i]: ",Image(Sequence([],create (Pp_("i") &
347: i := Gen_(.Izero,"i") & 1(GenJ_((i) ,"i"),Qq_("i"))))));
348: write("[Fibseq:i]: ",Image(Sequence([],create (Pp_("i") &
349: i := Gen_(Fibseq,"i") & 1(GenJ_((i) ,"i"),Qq_("i"))))));
350: write("[[i ^ 2]:F]: ",Image(Sequence([],create (Pp_("i") &
351: i := Gen_(Sequence([],create (Pp_("i") &
352: i := Gen_(Genseq_,"i") & 1(GenJ_((Binop_("^",i,2)) ,"i"),Qq_("i")))),"i") & 1(GenJ_((Ref_((Fibseq),i,"i")) ,"i"),Qq_("i"))))));
353: write("[[i ** 2]:F]: ",Image(Sequence([],create (Pp_("i") &
354: i := Gen_(Sequence([], create (1) | (4) | (9) | (16)),"i") & 1(GenJ_((Ref_((Fibseq),i,"i")) ,"i"),Qq_("i"))))));
355: write("[{1,3,5}:Abc!i]: ",Image(Sequence([],create (Pp_("i") &
356: i := Gen_(Sequence([], create (1) | (3) | (5)),"i") & 1(GenJ_((Ref_((Abc),i,"i")) ,"i"),Qq_("i"))))));
357: write("Iplus \\ 4: ",Image(Lim_((.Iplus) ,4),10));
358: write("[Iplus \\ 4:Abc!i]: ",Image(Sequence([],create (Pp_("i") &
359: i := Gen_(Lim_((.Iplus) ,4),"i") & 1(GenJ_((Ref_((Abc),i,"i")) ,"i"),Qq_("i")))),10));
360: end
361: procedure sec2_2();
362: write("[{i,i}]: ",Image(Sequence([],create (Pp_("i") &
363: i := Gen_(Genseq_,"i") & 1(GenJ_((Sequence([], create (i) | (i))) ,"i"),Qq_("i"))))));
364: end
365: procedure sec2_3();
366: k := 100;
367: write("[lambda(j)k + j]: ",Image(Sequence([],create (Pp_("j") &
368: j := Gen_(Genseq_,"j") & 1(GenJ_((Binop_("+",k,j)) ,"j"),Qq_("j"))))));
369: write("[F:lambda(j)k + j]: ",Image(Sequence([],create (Pp_("j") &
370: j := Gen_(Fibseq,"j") & 1(GenJ_((Binop_("+",k,j)) ,"j"),Qq_("j"))))));
371: write("[Abc:lambda(s)s || s]: ",Image(Sequence([],create (Pp_("s") &
372: s := Gen_(Abc,"s") & 1(GenJ_((Binop_("||",s,s)) ,"s"),Qq_("s"))))));
373: end
374: procedure sec2_4();
375: write("[lambda(i)[lambda(j) U!i || L!j]: ",Image(Sequence([],create (Pp_("i") &
376: i := Gen_(Genseq_,"i") & 1(GenJ_((Sequence([],create (Pp_("j") &
377: j := Gen_(Genseq_,"j") & 1(GenJ_((Binop_("||",Ref_((U),i,"i"),Ref_((L),j,"j"))) ,"j"),Qq_("j"))))) ,"i"),Qq_("i"))))));
378: write("[lambda(i)[lambda(j) U!j || L!i]: ",Image(Sequence([],create (Pp_("i") &
379: i := Gen_(Genseq_,"i") & 1(GenJ_((Sequence([],create (Pp_("j") &
380: j := Gen_(Genseq_,"j") & 1(GenJ_((Binop_("||",Ref_((U),j,"j"),Ref_((L),i,"i"))) ,"j"),Qq_("j"))))) ,"i"),Qq_("i"))))));
381: write("[Izero:lambda(j)[(Iplus %% j) \\ (j + 1):i]]: ",Image(Sequence([],create (Pp_("j") &
382: j := Gen_(.Izero,"j") & 1(GenJ_((Sequence([],create (Pp_("i") &
383: i := Gen_(Lim_(((Shift_((.Iplus),j))) ,(Binop_("+",j,1))),"i") & 1(GenJ_((i) ,"i"),Qq_("i"))))) ,"j"),Qq_("j"))))));
384: end
385: procedure sec3_1();
386: I := Sequence([], create (1) | (2) | (3) | (4) | (5) | (6));
387: J := Sequence([], create (100) | (200) | (300) | (400) | (500) | (600));
388: write("I + J: ",Image(Binop_("+",I,J)));
389: write("{a, ab, c} || {c, b, a}: ",Image(Binop_("||",Sequence([], create ("a") | ("ab") | ("c")),Sequence([], create ("c") | ("b") | ("a")))));
390: write("Abc || Abc: ",Image(Binop_("||",Abc,Abc)));
391: write("{1,2,3,4} + {1,4}: ",Image(Binop_("+",Sequence([], create (1) | (2) | (3) | (4)),Sequence([], create (1) | (4)))));
392: write("{a, ab, c} || {x}: ",Image(Binop_("||",Sequence([], create ("a") | ("ab") | ("c")),Sequence([], create ("x")))));
393: end
394: procedure sec3_2();
395: I := Sequence([], create (1) | (2) | (0) | (0) | (45) | (0));
396: write("[if I!i = 0 then {0} else {1}]: ",Image(Sequence([],create (Pp_("i") &
397: i := Gen_(Genseq_,"i") & 1(GenJ_((if Binop_("=",Ref_((I),i,"i"),0) then Sequence([], create (0)) else Sequence([], create (1))) ,"i"),Qq_("i"))))));
398: write("[if I!i = 0 then 0 else 1]: ",Image(Sequence([],create (Pp_("i") &
399: i := Gen_(Genseq_,"i") & 1(GenJ_((if Binop_("=",Ref_((I),i,"i"),0) then 0 else 1) ,"i"),Qq_("i"))))));
400: end
401: procedure sec3_3();
402: write("Red(Iplus \\ 5,+): ",Image(Red(Lim_((.Iplus) ,5),"+")));
403: write("[Red(F \\ i,+)]: ",Image(Sequence([],create (Pp_("i") &
404: i := Gen_(Genseq_,"i") & 1(GenJ_((Red(Lim_((Fibseq) ,i),"+")) ,"i"),Qq_("i"))))));
405: write("[Red(Abc \\ (i + 1),||)]: ",Image(Sequence([],create (Pp_("i") &
406: i := Gen_(Genseq_,"i") & 1(GenJ_((Red(Lim_((Abc) ,(Binop_("+",i,1))),"||")) ,"i"),Qq_("i"))))));
407: end
408: procedure sec4();
409: write("[if Iplus!i mod 2 = 0 then Iplus!i]: ",Image(Sequence([],create (Pp_("i") &
410: i := Gen_(Genseq_,"i") & 1(GenJ_((if Binop_("=",Binop_("%",Ref_((.Iplus),i,"i"),2),0) then Ref_((.Iplus),i,"i")) ,"i"),Qq_("i"))))));
411: write("[if |Abc!i| mod 2 = 0 then Abc!i]: ",Image(Sequence([],create (Pp_("i") &
412: i := Gen_(Genseq_,"i") & 1(GenJ_((if Binop_("=",Binop_("%",Unop_("*",(Ref_((Abc),i,"i"))),2),0) then Ref_((Abc),i,"i")) ,"i"),Qq_("i"))))));
413: write("[if i mod 2 = 1 then F!(i + 1) else F!(i - 1)]: ",Image(Sequence([],create (Pp_("i") &
414: i := Gen_(Genseq_,"i") & 1(GenJ_((if Binop_("=",Binop_("%",i,2),1) then Ref_((Fibseq),(Binop_("+",i,1)),) else Ref_((Fibseq),(Binop_("-",i,1)),)) ,"i"),Qq_("i")))),10));
415: write("[if i mod 2 = 1 then Iplus!i + Iplus!(i + 1)]: ",Image(Sequence([],create (Pp_("i") &
416: i := Gen_(Genseq_,"i") & 1(GenJ_((if Binop_("=",Binop_("%",i,2),1) then Binop_("+",Ref_((.Iplus),i,"i"),Ref_((.Iplus),(Binop_("+",i,1)),))) ,"i"),Qq_("i"))))));
417: I := Sequence([], create (0) | (1) | (2) | (3) | (0) | (2) | (0) | (5));
418: write("[if I!i = 0 then i]: ",Image(Sequence([],create (Pp_("i") &
419: i := Gen_(Genseq_,"i") & 1(GenJ_((if Binop_("=",Ref_((I),i,"i"),0) then i) ,"i"),Qq_("i"))))));
420: end
421: procedure sec5();
422: write("[Fib(i)]: ",Image(Sequence([],create (Pp_("i") &
423: i := Gen_(Genseq_,"i") & 1(GenJ_((Fib()) ,"i"),Qq_("i"))))));
424: write("[Fibs(i)]: ",Image(Sequence([],create (Pp_("i") &
425: i := Gen_(Genseq_,"i") & 1(GenJ_((Fibs()) ,"i"),Qq_("i"))))));
426: write("[G(i - 1)]: ",Image(Sequence([], create (0 | G()))));
427: write("[Izero:G(i)]: ",Image(Sequence([], create (0 | G()))));
428: write("[Izero:Gk(i,2)]: ",Image(Sequence([], create (Gk(2)))));
429: end
430: procedure Compress(X) # compression of X to scalar sequence
431: return Sequence([],create Collapse_(Copy(X)))
432: end
433:
434: procedure Copy(X) # copy X
435: local e, i
436: i := *X.a
437: return Sequence(copy(X.a),create Pre_(X.e,i))
438: end
439:
440: procedure Compose(f,X1,X2,X3,X4) # apply f in parallel
441: local a
442: end
443:
444: procedure Empty(X) # is X an empty sequence?
445: if /X then return Phi
446: if not(S_(X)) | (*X.a > 0) | put(X.a,@X.e) then fail
447: else return Phi
448: end
449:
450: procedure Image(X,i,r) # image of X to i values
451: local s, t, j
452: if S_(X) then {
453: /i := 5
454: /r := 0
455: if r >= i then return "{...}"
456: j := 0
457: s := "{"
458: every t := (Gen_(X) \ i) do {
459: s ||:= Image(t,i,r +:= 1) || ","
460: j +:= 1
461: }
462: if j = 0 then return "{}"
463: if Ref_(X,i + 1) then s ||:= "...,"
464: s[-1] := "}"
465: return s
466: }
467: else return image(X)
468: end
469:
470:
471: procedure ImageW(X,i,r) # image of X to i values
472: local s, t, j
473: if S_(X) then {
474: /i := 5
475: /r := 0
476: if r >= i then return "{...}"
477: j := 0
478: s := "{"
479: every t := (Gen_(X) \ i) do {
480: s ||:= write(ImageW(t,i,r +:= 1)) || ","
481: j +:= 1
482: }
483: if j = 0 then return "{}"
484: if Ref_(X,i + 1) then s ||:= "...,"
485: s[-1] := "}"
486: return s
487: }
488: else return image(X)
489: end
490:
491: procedure Index(X) # current size of X
492: if not S_(X) then return 1
493: return *X.a
494: end
495:
496: procedure Last(X) # produce all values of X
497: if not S_(X) then return X
498: return X.a[Length(X)]
499: end
500:
501: procedure Length(X) # length of X
502: if not S_(X) then return 1
503: while put(X.a,@X.e)
504: return *X.a
505: end
506:
507: procedure Next(X) # produce next value of X
508: local x
509: if not S_(X) then fail
510: if x := @X.e then {
511: put(X.a,x)
512: return x
513: }
514: end
515:
516: procedure Print(X,i) # write the image of a stream
517: Write(Image(X,i))
518: return X
519: end
520:
521: procedure Read(f) # sequence from file f
522: return Sequence([],create read(!f))
523: end
524:
525: procedure Red(X,op) # reduction of X over op
526: local S
527:
528: S := Seq_(X)
529: a := copy(S.a)
530: e := S.e
531: return Sequence([], create Red_(Sequence([], create !a | |@e),op))
532: end
533:
534: procedure Run(X,i) # force computation of next i elements
535:
536: if not S_(X) then return X
537: every 1 to i do
538: put(X.a,@X.e) | fail
539: return X
540: end
541:
542: procedure Subseq(X,i,j) # subsequence of X from i to j
543: return Lim_(Shift_(X,i-1),j - i + 1)
544: end
545:
546: procedure Trace(X,i) # image of X, returning X
547: write(Image(X,i))
548: return X
549: end
550:
551: procedure Write(X) # write elements in X with linefeeds
552: return Generic_(write,X)
553: end
554:
555: procedure Writes(X) # write elements in X without linefeeds
556: return Generic_(writes,X)
557: end
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