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1.1 root 1: .TH SNOCONE 1
2: .CT 1 prog_other
3: .SH NAME
4: snocone \- snobol with syntactic sugar
5: .SH SYNOPSIS
6: .B snocone
7: .I file ...
8: .SH DESCRIPTION
9: .I Snocone
10: is a programming language, syntactically
11: similar to C, that compiles into
12: .SM SNOBOL4.
13: The Snocone compiler translates the concatenation of all
14: the input files into a
15: .SM SNOBOL4
16: program, which it writes in
17: .FR a.out .
18: When
19: .F a.out
20: is executed, the
21: .SM SNOBOL4
22: interpreter will automatically be invoked.
23: A synopsis of Snocone syntax follows.
24: .SS Lexical conventions
25: .br
26: Everything after the first unquoted
27: .L #
28: on an input line is ignored.
29: .br
30: Statements normally end at the end of the line.
31: If the last character on a line is an operator,
32: open parenthesis or bracket, or comma, the statement is
33: continued on the next line.
34: .SS "Binary operators, \fRgrouped by decreasing precedence"
35: .TP
36: .B []
37: Array and table indexing (denoted in
38: .SM SNOBOL4
39: by
40: .LR <> ).
41: .PD 0
42: .TP
43: .B $ .
44: conditional and immediate pattern value assignment,
45: as in
46: .SM SNOBOL4
47: .TP
48: .B ^
49: power; right-associative as in
50: .SM SNOBOL4
51: .TP
52: .B * / %
53: multiplication, division, remainder;
54: unlike
55: .SM SNOBOL4,
56: all have the same precedence.
57: .TP
58: .B + -
59: addition, subtraction
60: .TP
61: .B
62: < > <= >= == != :<: :>: :<=: :>=: :==: :!=:
63: comparison operators; the ones surrounded by colons
64: compare strings, the others compare numbers.
65: These operators behave as
66: .SM SNOBOL4
67: predicates: they return
68: the null string if the condition is true,
69: and fail if it is false.
70: .TP
71: .B &&
72: concatenation;
73: evaluates its right operand
74: only after its left operand has been successfully
75: evaluated.
76: It therefore acts as logical
77: .I and
78: when applied to predicates.
79: The null string may be concatenated to any value.
80: .TP
81: .B |\^|
82: the value of the left operand if possible, otherwise
83: the value of the right operand.
84: .TP
85: .B |
86: pattern value alternation.
87: .TP
88: .B ?
89: pattern match.
90: Returns the part of the left operand matched by the
91: right operand, which must be a pattern.
92: May be used on the left of an assignment
93: if the left operand is appropriate.
94: Right-associative.
95: .TP
96: .B =
97: assignment
98: .PD
99: .SS Unary operators
100: .TP
101: .B +
102: The numeric equivalent of its argument.
103: .PD 0
104: .TP
105: .B -
106: The numeric equivalent of its argument, with the sign reversed.
107: .TP
108: .B *
109: Unevaluated expression, as in
110: .SM SNOBOL4.
111: .TP
112: .B $
113: If
114: .I v
115: is a value of type
116: .BR name ,
117: then
118: .BI $ v
119: is the variable of that name.
120: .TP
121: .B @
122: Pattern matching cursor assignment.
123: .TP
124: .B ~
125: Logical negation: returns the null string if its argument
126: fails, and fails otherwise.
127: .TP
128: .B ?
129: Returns the null string if its argument succeeds,
130: and fails otherwise.
131: .TP
132: .B \&.
133: Returns a value of type
134: .B name
135: that refers to its (lvalue) argument.
136: .PD
137: .SS Statements
138: .PP
139: Statements may be prefixed by one or more labels.
140: A label is an identifier followed by a colon, as in C.
141: All labels are global:
142: it is a good idea to prefix labels in procedures
143: with the name of the procedure.
144: .TP
145: .I expression
146: The given
147: .I expression
148: is evaluated for its side effects.
149: .TP
150: .BI { " statement ... " }
151: The
152: .I statements
153: are executed sequentially.
154: .TP
155: .BI "if (" expression ) " statement \fR[ " else " statement\fR ]"
156: If evaluation of the
157: .I expression
158: succeeds, the first
159: .I statement
160: is executed.
161: Otherwise, the second
162: .IR statement ,
163: if any, is executed.
164: An
165: .I else
166: belongs to the closest unmatched
167: .BR if .
168: .TP
169: .BI "while (" expression ") " statement
170: The
171: .I statement
172: is executed repeatedly, as long as the
173: .I expression
174: can be successfully evaluated.
175: .TP
176: .BI "do " statement " while (" expression )
177: Like the
178: .B while
179: statement, except that the
180: .I statement
181: is executed once before the first time the
182: .I expression
183: is evaluated.
184: .TP
185: .B
186: for (\fIe1\fP, \fIe2\fP, \fIe3\fP) \fIstatement\fP
187: As in C, except that commas are used instead of semicolons.
188: .TP
189: .BR return " [\fIexpression\fP]"
190: returns the value of the
191: .I expression
192: from the current function.
193: If
194: .I expression
195: fails or is missing, the value returned is that of the
196: variable with the same name as the function.
197: If that variable was never set, the function returns
198: the null string.
199: .TP
200: .BR nreturn " [\fIexpression\fP]"
201: The
202: .I expression
203: must be the name of a variable.
204: That variable is returned from the current
205: function as an lvalue.
206: If the
207: .I expression
208: fails or is missing, the variable with the
209: same name as the function must have been set to the
210: name of a variable.
211: .TP
212: .B freturn
213: The current function returns failure.
214: .TP
215: .BI goto " label"
216: Transfer control to the given
217: .I label.
218: .HP Procedures
219: .PP
220: Procedures may not be textually nested, but may be recursive
221: and may call each other in forward references.
222: The general form of a procedure declaration is:
223: .IP
224: .B
225: procedure \fIname\fP (\fIargs\fP) \fIlocals\fP { \fIstatement ... \fP}
226: .PP
227: The
228: .I args
229: and
230: .I locals
231: are lists of variable names, separated by commas.
232: Since Snocone is a dynamically typed language, further
233: declarations are not necessary.
234: Although procedures are not textually nested, names are
235: dynamically scoped: a procedure can reference the local variables
236: and parameters of its caller as if they were global variables.
237: .HP Input-Output
238: .PP
239: Assigning a (string) value to the variable
240: .L output
241: causes that value to be written as a single line on the
242: standard output.
243: Accessing the variable
244: .L input
245: causes a line to be read from the standard input.
246: The access fails at end of file.
247: Accessing or assigning to the variable
248: .L terminal
249: causes a line to be read from or written to the
250: standard error file.
251: Other input-output is as implemented by
252: the Macrospitbol interpreter; see
253: .IR langs (1).
254: .SH SEE ALSO
255: A. R. Koenig,
256: `The Snocone Programming Language',
257: this manual, Volume 2
258: .br
259: .IR langs (1)
260: .SH BUGS
261: Run-time diagnostics refer to
262: .SM SNOBOL4
263: source statement numbers,
264: not to Snocone line numbers.
265: .br
266: Extremely long statements can overflow the
267: .SM SNOBOL4
268: compiler's
269: limits on input line length.
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