116:. These represent, respectively, the right to ask the value of the variable (or some characteristic of the value) and the right to tell the value (or to tell some constraint on what the value can be). The asker and teller aspects can be passed around as arguments independently of each other. Neither right implies the other right. The syntax of the language prevents copying a teller or exercising it more than once. Logical contradiction is statically prevented, according to Kahn and Saraswat.
97:, namely that the order of arrival of the messages is not guaranteed. However, unlike actors in the actor model, processes in Janus can pass around their "mailboxes" so to speak, in the form of bags, and can hold more than one. This ability to pass mailboxes around and hold more than one is inherited in computer programming language
90:. Code that needs to send a message to a process does so by constraining a bag to be the union of another bag and the singleton bag of the message. The other bag is then available to be constrained for sending subsequent messages.
175:
David
Gudeman, Koenraad De Bosschere, Saumya K. Debray (1992). "jc: An Efficient and Portable Sequential Implementation of Janus". Proc. Joint International Conference and Symposium on Logic Programming.
93:
The process receives the message by matching the bag to a pattern that says it is the union of some singleton and some other bag. The logic of the bag channels produces a property shared by the
108:, the two-faced Roman god, because every logical variable in Janus has as its two "faces", two aspects that can be passed as arguments. These are called the
79:
partially described by K. Kahn and Vijay A. Saraswat in the paper "Actors as a special case of concurrent constraint (logic) programming" in 1990. It is a
198:
188:
80:
27:
98:
193:
59:
76:
172:
VA Saraswat, M Rinard, P Panangaden (1991). "The semantic foundations of concurrent constraint programming." POPL.
169:
VA Saraswat, KM Kahn, J Levy (1990). "Janus: A step towards distributed constraint programming." NACLP.
43:
22:
105:
39:
146:
34:
182:
134:
94:
150:
135:"Actors as a special case of concurrent constraint (logic) programming"
57:
49:
33:
21:
104:Janus, the programming language, is named after
133:Kahn, K.; Saraswat, Vijay A. (1 October 1990).
8:
86:Janus models concurrency through the use of
16:
15:
125:
7:
14:
199:Constraint programming languages
189:Concurrent programming languages
101:, which is influenced by Janus.
83:language without backtracking.
1:
77:computer programming language
194:Logic programming languages
28:concurrent constraint logic
215:
65:
81:concurrent constraint
151:10.1145/97946.97955
139:ACM SIGPLAN Notices
50:First appeared
18:
70:
69:
44:Vijay A. Saraswat
206:
162:
161:
159:
157:
130:
66:(none available)
35:Designed by
19:
214:
213:
209:
208:
207:
205:
204:
203:
179:
178:
166:
165:
155:
153:
132:
131:
127:
122:
60:implementations
12:
11:
5:
212:
210:
202:
201:
196:
191:
181:
180:
177:
176:
173:
170:
164:
163:
124:
123:
121:
118:
68:
67:
63:
62:
55:
54:
51:
47:
46:
37:
31:
30:
25:
13:
10:
9:
6:
4:
3:
2:
211:
200:
197:
195:
192:
190:
187:
186:
184:
174:
171:
168:
167:
152:
148:
145:(10): 57–66.
144:
140:
136:
129:
126:
119:
117:
115:
111:
107:
102:
100:
96:
91:
89:
84:
82:
78:
74:
64:
61:
56:
52:
48:
45:
41:
38:
36:
32:
29:
26:
24:
20:
154:. Retrieved
142:
138:
128:
113:
109:
103:
92:
88:bag channels
87:
85:
72:
71:
95:actor model
183:Categories
156:29 October
120:References
112:and the
99:ToonTalk
40:Ken Kahn
23:Paradigm
114:teller
58:Major
110:asker
106:Janus
75:is a
73:Janus
17:Janus
158:2019
53:1990
42:and
147:doi
185::
143:25
141:.
137:.
160:.
149::
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.