MemCPs native access technology is the scheme scripting language.<\/p>\n\n\n\n\n\n\n\n
In scheme, you can do functional programming with scheme. This is an example scheme terminal session in MemCP:<\/p>\n\n\n\n
carli@launix-MS-7C51<\/b><\/font>:~\/projekte\/memcp<\/b><\/font>$ make && .\/memcp \ngo build\nmemcp Copyright (C) 2023 Carl-Philip H\u00e4nsch\n This program comes with ABSOLUTELY NO WARRANTY;\n This is free software, and you are welcome to redistribute it\n under certain conditions;\nWelcome to memcp\nHallo World\nMySQL server listening on port 3307 (connect with mysql -P 3307 -u user -p)\nlistening on http:\/\/localhost:4321\n><\/font> (createdatabase \"test\")\n=<\/font> \"ok\"\n><\/font> (createtable \"test\" \"foo\" '('(\"bar\" \"int\" '() \"\")))\n=<\/font> \"ok\"\n><\/font> (insert \"test\" \"foo\" '(\"bar\" 12))\n=<\/font> \"ok\"\n><\/font> (scan \"test\" \"foo\" (lambda () true) (lambda (bar) (print \"bar=\" bar)))\nbar=12\n=<\/font> \"47.631\u00b5s\"\n><\/font> \n<\/pre>\n\n\n\nAs you can see, MemCP has some functions like createdatabase<\/code>, createtable<\/code>, insert<\/code> and scan<\/code>. Whereof which the first three are straight forward while scan<\/code> is the interesting part:<\/p>\n\n\n\nThe interface of scan<\/code> is the following:<\/p>\n\n\n\n(scan schema table filterfn mapfn [reducefn [default]])<\/code><\/p>\n\n\n\nThe interesting part is filterfn<\/code>. In the filter function, you specify the condition that must apply on a dataset in order to be scanned. An example for a filter function might be (lambda (ID) (equal? ID 34))<\/code>. This would only scan entries that have an ID<\/code> equal to 34<\/code>. <\/p>\n\n\n\nThe arguments of the filter function represent the columns of the table. This means, in a columnar storage, in order to find out the items whose conditions fit the scan condition, only the specified columns have to be opened.<\/em><\/p>\n\n\n\nThe same applies for the map function. Inside the map function, you can compute whatever you want to take away from the scanned row. This might be a single value, this might be stitching together a JOIN dataset … whatever you want.<\/p>\n\n\n\n
Map and reduce are made to be completely parallelizable, so you cannot rely on their execution order – which does not matter because our scheme dialect is pure functional.<\/p>\n\n\n\n
Finally, the reducefn will do aggregation.<\/p>\n","protected":false},"excerpt":{"rendered":"
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MemCPs native access technology is the scheme scripting language. In scheme, you can do functional programming with scheme. This is an example scheme terminal session in MemCP: carli@launix-MS-7C51:~\/projekte\/memcp$ make && .\/memcp go build memcp Copyright (C) 2023 Carl-Philip H\u00e4nsch This program comes with ABSOLUTELY NO WARRANTY; This is free software, and you are welcome to redistribute it under certain conditions; Welcome to memcp Hallo World MySQL server listening on port 3307 (connect with mysql -P 3307 -u user -p) listening on http:\/\/localhost:4321 > (createdatabase “test”) = “ok” > (createtable “test” “foo” ‘(‘(“bar” “int” ‘() “”))) = “ok” > (insert “test”…<\/p>\n","category_list_v2":"MemCP<\/a>, Programming<\/a>","author_info_v2":{"name":"Carl-Philip H\u00e4nsch","url":"https:\/\/launix.de\/launix\/en\/author\/carli\/"},"comments_num_v2":"0 comments","uagb_featured_image_src":{"full":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920.jpg",1920,1277,false],"thumbnail":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920-150x150.jpg",150,150,true],"medium":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920-300x200.jpg",300,200,true],"medium_large":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920-768x511.jpg",751,500,true],"large":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920-1024x681.jpg",751,499,true],"1536x1536":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920-1536x1022.jpg",1536,1022,true],"2048x2048":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920.jpg",1920,1277,false],"trp-custom-language-flag":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920.jpg",18,12,false],"xs-thumb":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920-64x64.jpg",64,64,true],"appku-shop-single":["https:\/\/launix.de\/launix\/wp-content\/uploads\/2023\/02\/storage-warehouse-1553550_1920.jpg",620,412,false]},"uagb_author_info":{"display_name":"Carl-Philip H\u00e4nsch","author_link":"https:\/\/launix.de\/launix\/en\/author\/carli\/"},"uagb_comment_info":0,"uagb_excerpt":"MemCPs native access technology is the scheme scripting language.","_links":{"self":[{"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/posts\/4872","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/comments?post=4872"}],"version-history":[{"count":3,"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/posts\/4872\/revisions"}],"predecessor-version":[{"id":4885,"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/posts\/4872\/revisions\/4885"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/media\/4873"}],"wp:attachment":[{"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/media?parent=4872"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/categories?post=4872"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/launix.de\/launix\/en\/wp-json\/wp\/v2\/tags?post=4872"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}