1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
|
Mew is a library targetting R5RS/R7RS scheme, which provides some
conveniences inspired from Goo, Clojure, T and Arc to allow writing more
compact code.
== Design goals
Mew, in its current iteration, is designed as a Scheme library. Even
though a program written in Mew will look quite different to a plain
Scheme program, code is compatible, and Scheme code can generally live
inside a Mew program, and Mew can load Scheme libraries. Extra care
has been taken to not reuse identifiers found in important SRFIs.
Mew code is tight code, commonly used Mew identifiers are short.
Mew uses a few features provided by R7RS internally, but does not
require using R7RS.
Mew targets Chicken Scheme currently but should be easy to port to
other Scheme implementations.
Mew is multi-paradigm: it simplifies both writing imperative and
functional code.
Mew uses SRFI-158 (Generators and Accumulators) for generic functions
on enumerable structures.
Mew generally uses {{equal?}} as equality predicate.
Mew never mutates lists.
Except for few shortcut macros ({{op}} and {{op*}),
Mew endorses macro hygiene.
== Re-Exports
Mew re-exports
SRFI-1 (List library),
SRFI-13 (String Libraries) (from {{utf8-srfi-13}}),
SRFI-69 (Basic hash tables),
SRFI-158 (Generators and Accumulators),
{{(chicken io)}},
{{(chicken irregex)}},
{{(chicken pretty-print)}}},
{{(chicken sort)}}},
and {{matchable}}.
== Definitions, bindings and assignments
<syntax>(def <variable> <expression>)</syntax>
<syntax>(def (<variable> <formals>) <expression>)</syntax>
Alias for {{define}}.
<syntax>(fun <formals> <body>...)</syntax>
Alias for {{lambda}}.
<syntax>(fun* <pattern> <body>...)</syntax>
Lambda which pattern matches all its arguments (ala the {{match}} macro).
<syntax>(loc (<pat1> <val1> ... <patN> <valN>) <body>)</syntax>
Binds local variables in pattern (ala the {{match}} macro)
{{pat1}} to the result of evaluating {{val1}},
then {{pat2}} to {{val2}}, etc., then evaluates {{body}}.
Assignments can refer to previously assigned values of the {{loc}}.
<syntax>(andloc (<var1> <val1> ... <varN> <valN>) <body>)</syntax>
Like {{loc}} (without pattern matching), but return false when one of
the {{<valN>>}} evaluates to false. If a {{<valN>}} is {{_}},
only performs the check without binding a value.
<syntax>(rec <name> <expression>)</syntax>
<syntax>(rec (<name> <formals>) <expression>)</syntax>
See Module%20(chicken%20base)#rec or SRFI-31.
Often, using {{def}} in an inner scope is preferable to using {{rec}}.
<syntax>(set <location> <expression>)</syntax>
Like {{set!}}, but also return the value of {{<expression>}}.
== Control flow
<syntax>(esc <escape> <body>)</syntax>
Bind {{<escape>}} to the current continuation, then run {{<body>}}.
Code should not pass {{<escape>}} outside the lexical scope
and only call it once---use {{call/cc}} else.
<syntax>(fin <body> . <cleanup>)</syntax>
Evaluate {{<body>}}, then evaluate {{<cleanup>}}, even if {{<body>}}
used a non-local exit (as from {{esc}}).
Returns value of {{<body>}}, so can also be used as a replacment
for Common Lisp PROG1.
<syntax>(rep <name> (<var1> <init1> ... <varN> <initN>) <body>...)</syntax>
Explicit form of named {{let}}, using {{loc}} binding syntax.
Assignments cannot refer to previously assigned values of the {{rep}}.
<syntax>(seq . <body>)</syntax>
Like {{begin}}, but allows {{<body>}} to be empty and returns a value
which is {{void?}} then.
<syntax>(unless <cond> <expr>...)</syntax>
<syntax>(when <cond> <expr>...)</syntax>
As in R7RS-small.
<syntax>(while <cond> <expr>...)</syntax>
<syntax>(until <cond> <expr>...)</syntax>
Evaluate {{<expr>}} while {{<cond>}} is true/false.
<syntax>(xcond <cases>...)<syntax>
Like {{cond}}, but raise error if no case matched.
<syntax>(fail <type>? <message> <args>...)</syntax>
Create and signal a condition of {{<type>}} (default: {{(exn)}})
with a {{'message}} of {{<message>}} passed through {{format}} with
{{<args>}}.
== Numeric helpers
<procedure>(inc <num>)</procedure>
<procedure>(dec <num>)</procedure>
Increment or decrement the argument by 1.
<procedure>(div <num> <num>)</procedure>
Alias for {{floor-quotient}}.
<procedure>(mod <num> <num>)</procedure>
Alias for {{floor-remainder}}.
== General helpers
<procedure>(app <proc> . <args>)</procedure>
Alias for {{apply}}.
<syntax>(op <form>)</syntax>
Returns a procedure that evaluates {{<form>}} with {{_}} bound to its
only argument.
If {{<form>>} is empty, behaves as {{values}}, i.e. the identity function.
{{(op 5)}} is the function that always returns 5.
{{(op + 2 _)}} is the function that adds 2 to its argument.
<syntax>(op* <form>)</syntax>
Returns a procedure that evaluates {{<form>}} with {{...}} expanded
to all its arguments. {{...}} must only appear once and must not
be nested further. If {{...} does not appear in {{<form>}}, it's
added implicitly at the end.
{{(op* + 5)}} is the function that adds 5 and then all its arguments.
{{(op* - 0 ... 2)}} is the function that subtracts all its arguments from 0
and finally 2.
<syntax>(proj <N>)</syntax>
Expands to a function that returns its {{<N>}}th argument.
<procedure>(boolean <obj>)</procedure>
Return false if {{<obj>}} is {{#f}}, and true else.
<procedure>(negate <fun>)</procedure>
Alias for {{complement}}.
<procedure>(comp <fun>...)</procedure>
Alias for {{compose}}.
<procedure>(per <fun>...)</procedure>
Reverse function composition.
<procedure>(act <obj> <fun>...)</procedure>
Reverse function compose all {{<fun>}}, then apply to {{<obj>}}.
<procedure>(=> <obj> <fun>...)</procedure>
Alias for {{act}}.
<syntax>(set=> <loc> <fun>...)</set>
Shortcut for {{(set <loc> (=> <loc> <fun>...))}}.
<procedure>(and=> <obj> <fun>...)</procedure>
Apply the first function in {{<fun>}} to {{<obj>}}, then the second to
the result, etc. Stop if any value is false.
<procedure>(juxt <fun>...)</procedure>
Returns a function that applies each {{<fun>}} to its arguments and
returns the results as multiple values.
<procedure>(unlist <list>)</procedure>
Returns the list {{<list>}} as multiple values.
<procedure>(str . <args>)</procedure>
Returns a new string composed by concatenating the strings given by
applying {{display}} to all {{<args>}}.
<syntax>(one-of <val>...)</syntax>
Expands to a lambda expression that is true if its argument is
{{equal?}} to any of the {{<val>}} passed.
<procedure>(sing? <list>)</procedure>
Return true iff {{<list>}} is a proper list of length 1.
<procedure>(void <args>...)</procedure>
Ignores all arguments and returns a value where {{void?}} is true.
<procedure>(void? <val>)</procedure>
Returns true if {{<va>}} is an unspecified value, else false.
<procedure>(scan <kons> <knil> <lists>...)</procedure>
<procedure>(scan-right <kons> <knil> <lists>...)</procedure>
Like {{fold}}/{{fold-right}}, but collects all accumulator values.
Prefer {{xscan}}/{{xscan-right}}.
<procedure>(xfold <kons> <knil> <lists>...)</procedure>
<procedure>(xfold-right <kons> <knil> <lists>...)</procedure>
<procedure>(xreduce <kons> <knil> <lists>...)</procedure>
<procedure>(xreduce-right <kons> <knil> <lists>...)</procedure>
<procedure>(xscan <kons> <knil> <lists>...)</procedure>
<procedure>(xscan-right <kons> <knil> <lists>...)</procedure>
Like {{fold}}/{{fold-right}}/{{reduce}}/{{reduce-right}}/{{scan}}/{{scan-right}},
but {{<kons>}} always takes the accumulator as first arguments,
and the items after. This is more practical when multiple {{lists}}
are passed.
<syntax>(imp <antedecent>... <consequent>)<syntax>
Material implication: evaluate {{<antedecent>...}} until one is false,
then shortcut and return true. If all {{<antedecent>...}} are true,
evaluate {{<consequent>}}.
== I/O helpers
<procedure>(prn . <args>)</procedure>
{{write}} all {{args}} separated by spaces and terminated by a newline
to the current output stream. Returns the value of the last argument.
<procedure>(puts . <args>)</procedure>
{{display}} all {{args}} terminated by a newline to the current output stream.
<procedure>(eof)</procedure>
Return an object for which {{eof-object?}} is true.
<procedure>(slurp <obj>)</procedure>
If {{<obj>}} is an input-port, read all data into a string.
If {{<obj>}} is a string, read all data from the file named {{<<obj>>}.
If {{<obj>}} is false, read all data from {{*current-input-port*}}.
== Equality
<procedure>(=? <val>...)</procedure>
Return true if all values are {{equal?}} or hash-tables with same
set of keys and {{equal?}} values.
<procedure>(<>? <val1> <val2> ...)</procedure>
Return true if all values are pairwise different.
== Data types
<procedure>(get <obj> <idx>)</procedure>
<procedure>(at <obj> <idx>)</procedure>
<procedure>(set (at <obj> <idx>) <val>)</procedure>
Generalized accessor, supports indexing into lists, vectors,
hash-tables, strings.
<procedure>(set-at <obj> <key1> <val1>...)</procedure>
Mutate the hash-table/vector/string {{<obj>}} by setting
the key/index {{<key1>}} to {{<val1>}} etc.
Returns {{<obj>}}.
<procedure>(del-at <hash-table> <key>...)</procedure>
Delete {{<key>}} from the hash-table, and return the hash-table.
<procedure>(tbl <key1> <val1> ... <keyN> <valN>)</procedure>
Construct a hash-table; using {{equal?}}.
<procedure>(keys <hash-table>)</procedure>
Alias for {{hash-table-keys}}.
<procedure>(vals <hash-table>)</procedure>
Alias for {{hash-table-values}}.
<procedure>(empty? <obj>)</procedure>
Test if {{<obj>}} is an empty list/string/vector/hash-table.
<procedure>(len <obj>)</procedure>
Return the length of the list/vector/string/hash-table/generator {{<obj>}}.
<syntax>(for (<var> <obj>) <body>...)</syntax>
<syntax>(for ((<key> . <val>) <tbl>) <body>...)</syntax>
If {{<obj>}} is a list or a vector, iterate over its elements.
If {{<obj>}} is a procedure, consider it a SRFI-158 generator
and iterate over its values.
If {{<obj>}} is a hash-table, iterate over its keys and values.
<procedure>(search <needle> <haystack> <offset>?)</procedure>
Returns the offset of the sequence (string/list/vector) {{<needle>}}
in the sequence {{<haystack>}},
starting no earlier than {{<offset>>}} (default: 0).
Returns false if the sequence cannot be found.
== Generators and Accumulators
<procedure>(gen <val>)</procedure>
Generic generator for list/vector/string/hash-table/generator.
<procedure>(cycle <val>...)</procedure>
Alias for {{circular-generator}}.
<procedure>(range <start>? <end>? <step>?)</procedure>
A variant of {{make-range-generator}} that also allows negative {{<step>}}.
{{<start>}} defaults to zero.
{{<end>}} defaults to infinity.
{{<step>}} defaults to 1.
<procedure>(giterate <fun> <val>)</procedure>
Generator returning {{<val>}}, {{(<fun> <val>)}}, {{(<fun> (<fun (<val>)))}}...
<procedure>(gconcatenate <gen>)</procedure>
Generator yielding all values of the all generators yielded by {{<gen>}}.
<procedure>(gpick <function> <gen>)<procedure>
Like {{gmap}}, apply {{<function>}} to all values yielded by
the generator {{<gen>}}, but skip values when {{<function>}} returns
an eof object.
<procedure>(gwindow <gen> <len>)</procedure>
Generator yielding a sliding window of length {{<len>}} (as a list)
over the values yielded by the generator {{<gen>}}. Yields never if
the generator yielded fewer than {{<len>}} elements.
<procedure>(gslice-when <pred> <gen>)</procedure>
Partition the elements yielded by the generator {{<gen>}} into lists:
starts a new list when the predicate {{<pred>}} called with the
previous and the current element of the generator returns true.
<procedure>(genumerate <gen>)</procedure>
Takes the values yielded by the generator {{<gen>}} and yields them as
a {{cons}} where the first cell is an index incremented on every
yield.
<procedure>(gfix <gen>)</procedure>
Returns a generator that runs the generator {{<gen>}} until it yields
a value {{equal?}} to the preceding one, then stops.
<procedure>(final <gen>)</procedure>
Run the generator {{<gen>}} until it stops and return its final value.
<procedure>(into <acc> <gen>...)</procedure>
Feed all elements of the generators {{<gen>}} into the accumulator {{<acc>}}.
Uses {{gen}} to convert {{<gen>}} into a generator.
If {{<acc>}} is a list/vector/hash-table/string, accumulate into
a corresponding accumulator initialized to {{<acc>}}.
<syntax>(accumulate (<var> <acc>) body ...)</syntax>
Bind {{<var>}} to the accumulator {{<var>}} and run {{body}}.
Finally, return the result of accumulation.
If {{<acc>}} is a list/vector/hash-table/string, accumulate into
a corresponding accumulator initialized to {{<acc>}}.
<procedure>(tally-accumulator)</procedure>
Returns an accumulator that counts how often each element was
accumulated. The accumulator results in a hash-table of objects to
numbers.
<procedure>(group-by-accumulator <f>)</procedure>
Returns an accumulator that stores all elements in lists in a hash-table,
applying {{<f>}} to the element to compute the key.
<procedure>(uniq-accumulator <f>?)</procedure>
Returns an accumulator that returns a list of unique elements.
Two elements are considered equal if their image under {{<f>}} is {{equal?}}.
{{<f>}} defaults to the identity function.
<procedure>(generator-xfold <f> <seed> <generators>...)</procedure>
Like {{generator-fold}}, but {{<f>}} always takes the accumulator as
first arguments, and the items after. This is more practical when
multiple {{<generators>}} are passed.
<procedure>(inject <f> <init>? <g>?)</procedure>
Returns a procedure that takes an generator (or something convertible
by {{gen}}) and xfolds the function {{<f>}} over its values. If given,
folding starts with {{<init>}}, else with the first element yielded by
the generator. If the generator is empty, return {{(<f>)}}.
If {{<g>}} is passed, immediately fold over the generator {{<g>}}.
<procedure>(odometer <wheels>...)</procedure>
Returns a generator that takes a list of numbers and yields all
combinations of numbers such that each is below it's wheel. The
rightmost number changes most quickly.
<procedure>(cross-product <obj>...)</procedure>
Returns a generator that takes multiple lists/vectors/strings and
yields all elements of their cartesian product (as lists).
== Regular expressions
<procedure>(?~ <str> <irx>)</procedure>
Matches the string {{<str>}} against the irregex (string or sexp) {{<irx>}}
without anchoring. Returns false on no match, else a list of all
match data strings.
<procedure>(gmatch <irx> <str>)</procedure>
Returns a generator that for each match of the irregex {{<irx>}} in
the string {{<str>}} either yields the match, or a list of all
match data strings (if there are any).
<procedure>(gsplit <irx> <str> <max>?)</procedure>
Returns a generator that yields the strings between matches of the
irregex {{<irx>}} in the string {{<str>}}, at most {{<max>>} times
(by default, unlimited).
When the pattern {{<irx>}} uses match data, the result is unspecified.
== Special syntax
<syntax>(-> a -> b c -> d e f)</syntax>
<syntax>(-> a ->> b c ->> d e f)</syntax>
Nesting macros: {{->}} inserts the previous part as the second argument:
{{(-> a -> b c -> d e f)}} expands to {{(d (b a c) e f)}}.
{{->>}} inserts the previous part as the last argument:
{{(-> a ->> b c ->> d e f)}} expands to {{(d e f (b c a))}}.
You can mix {{->}} and {{->>}} macros:
{{(-> a -> b c ->> d e f)}} expands to {{(d e f (b a c))}}.
Nesting macros must start off with a {{->}}.
<syntax>(fun-> b c -> d e f)</syntax>
<syntax>(fun->> b c ->> d e f)</syntax>
Nesting lambdas: like {{->}} but the nesting starts with the argument
of the lambda.
{{(fun-> b c -> d e f)}} expands to {{(lambda (x) (-> x -> b c -> d e f))}}.
{{(fun->> b c ->> d e f)}} expands to {{(lambda (x) (-> x ->> b c ->> d e f))}}.
<syntax>(set-> loc ...)</syntax>
Mutation with nesting macros: shortcut for {{(set loc (-> loc ...))}}.
<syntax>(-> ... if-> <val> <cond> <then> <else>?)<syntax>
Evaluate {{<val>}}. Then, when {{<cond>}} is not false, behaves like
{{(-> <val> -> <then>}}, otherwise like {{(-> <val> -> <else>)}}
(or just {{<val>}} if no {{<else>}} was passed).
<syntax>(-> ... and-> ...)<syntax>
<syntax>(-> ... and->> ...)<syntax>
Like {{->}}/{{->>}} but skips nesting the code if the nested
expression is false.
|
