| 1 | ---
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| 2 | in_progress: yes
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| 3 | default_highlighter: oils-sh
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| 4 | ---
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| 5 |
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| 6 | Streams, Tables and Processes - awk, R, xargs
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| 7 | =============================================
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| 8 |
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| 9 | *(July 2024)*
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| 10 |
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| 11 | This is a long, "unified/orthogonal" design for:
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| 12 |
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| 13 | - Streams: [awk]($xref) delimited lines, regexes
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| 14 | - Tables: like data frames with R's dplyr or Pandas, but with the "exterior"
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| 15 | TSV8 format
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| 16 | - Processes: xargs -P in parallel
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| 17 |
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| 18 | There's also a relation to:
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| 19 |
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| 20 | - Trees: `jq`, which will be covered elsewhere.
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| 21 |
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| 22 | It's a layered design. That means we need some underlying mechanisms:
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| 23 |
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| 24 | - `eval` and positional args `$1 $2 $3`
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| 25 | - `ctx` builtin
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| 26 | - Data langauges: TSV8
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| 27 | - Process pool / event loop primitive
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| 28 |
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| 29 | It will link to:
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| 30 |
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| 31 | - Oils blog posts (old)
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| 32 | - Zulip threads (recent)
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| 33 | - Other related projects (many of them)
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| 34 |
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| 35 | <div id="toc">
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| 36 | </div>
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| 37 |
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| 38 | ## Intro With Code Snippets
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| 39 |
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| 40 | Let's introduce this with a text file
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| 41 |
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| 42 | $ seq 4 | xargs -n 2 | tee test.txt
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| 43 | 1 2
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| 44 | 3 4
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| 45 |
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| 46 | xargs does splitting:
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| 47 |
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| 48 | $ echo 'alice bob' | xargs -n 1 -- echo hi | tee test2.txt
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| 49 | hi alice
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| 50 | hi bob
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| 51 |
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| 52 | Oils:
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| 53 |
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| 54 | # should we use $_ for _word _line _row? $[_.age] instead of $[_row.age]
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| 55 | $ echo 'alice bob' | each-word { echo "hi $_" } | tee test2.txt
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| 56 | hi alice
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| 57 | hi bob
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| 58 |
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| 59 | Normally this should be balanced
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| 60 |
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| 61 | ### Streams - awk
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| 62 |
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| 63 | Now let's use awk:
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| 64 |
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| 65 | $ cat test.txt | awk '{ print $2 " " $1 }'
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| 66 | 2 1
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| 67 | 4 3
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| 68 |
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| 69 | In YSH:
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| 70 |
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| 71 | $ cat test.txt | chop '$2 $1'
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| 72 | 2 1
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| 73 | 4 3
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| 74 |
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| 75 | It's shorter! `chop` is an alias for `split-by (space=true, template='$2 $1')`
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| 76 |
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| 77 | With a template, for static parsing:
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| 78 |
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| 79 | $ cat test.txt | chop (^"$2 $1")
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| 80 | 2 1
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| 81 | 4 3
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| 82 |
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| 83 | It's shorter! With a block:
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| 84 |
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| 85 | $ cat test.txt | chop { mkdir -v -p $2/$1 }
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| 86 | mkdir: created directory '2/1'
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| 87 | mkdir: created directory '4/3'
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| 88 |
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| 89 | With no argument, it prints a table:
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| 90 |
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| 91 | $ cat test.txt | chop
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| 92 | #.tsv8 $1 $2
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| 93 | 2 1
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| 94 | 4 3
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| 95 |
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| 96 | $ cat test.txt | chop (names = :|a b|)
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| 97 | #.tsv8 a b
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| 98 | 2 1
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| 99 | 4 3
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| 100 |
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| 101 | Longer examples with split-by:
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| 102 |
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| 103 | $ cat test.txt | split-by (space=true, template='$2 $1')
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| 104 | $ cat test.txt | split-by (space=true, template=^"$2 $1")
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| 105 | $ cat test.txt | split-by (space=true) { mkdir -v -p $2/$1 }
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| 106 | $ cat test.txt | split-by (space=true)
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| 107 | $ cat test.txt | split-by (space=true, names= :|a b|)
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| 108 | $ cat test.txt | split-by (space=true, names= :|a b|) {
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| 109 | mkdir -v -p $a/$b
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| 110 | }
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| 111 |
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| 112 | With must-match:
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| 113 |
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| 114 | $ var p = /<capture d+> s+ </capture d+>/
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| 115 | $ cat test.txt | must-match (p, template='$2 $1')
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| 116 | $ cat test.txt | must-match (p, template=^"$2 $1")
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| 117 | $ cat test.txt | must-match (p) { mkdir -v -p $2/$1 }
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| 118 | $ cat test.txt | must-match (p)
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| 119 |
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| 120 | With names:
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| 121 |
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| 122 | $ var p = /<capture d+ as a> s+ </capture d+ as b>/
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| 123 | $ cat test.txt | must-match (p, template='$b $a')
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| 124 | $ cat test.txt | must-match (p)
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| 125 | #.tsv8 a b
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| 126 | 2 1
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| 127 | 4 3
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| 128 |
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| 129 | $ cat test.txt | must-match (p) {
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| 130 | mkdir -v -p $a/$b
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| 131 | }
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| 132 |
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| 133 | Doing it in parallel:
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| 134 |
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| 135 | $ cat test.txt | must-match --max-jobs 4 (p) {
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| 136 | mkdir -v -p $a/$b
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| 137 | }
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| 138 |
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| 139 | ### Tables - Data frames with dplyr (R)
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| 140 |
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| 141 | $ cat table.txt
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| 142 | size path
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| 143 | 3 foo.txt
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| 144 | 20 bar.jpg
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| 145 |
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| 146 | $ R
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| 147 | > t=read.table('table.txt', header=T)
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| 148 | > t
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| 149 | size path
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| 150 | 1 3 foo.txt
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| 151 | 2 20 bar.jpg
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| 152 |
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| 153 | ### Processes - xargs
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| 154 |
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| 155 | We already saw this! Because we "compressed" awk and xargs together
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| 156 |
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| 157 | What's not in the streams / awk example above:
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| 158 |
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| 159 | - `BEGIN END` - that can be separate
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| 160 | - `when [$1 ~ /d+/] { }`
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| 161 |
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| 162 | ## Background / References
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| 163 |
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| 164 | - Shell, Awk, and Make Should be Combined (2016)
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| 165 | - this is the Awk part!
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| 166 |
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| 167 | - What is a Data Frame? (2018)
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| 168 |
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| 169 | - Sketches of YSH Features (June 2023) - can we express things in YSH?
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| 170 | - Zulip: Oils Layering / Self-hosting
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| 171 |
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| 172 | - Language Compositionality Test: J8 Lines
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| 173 | - This whole thing is a compositionality test
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| 174 |
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| 175 | - read --split
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| 176 | - more feedback from Aidan and Samuel
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| 177 |
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| 178 | - What is a Data Frame?
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| 179 |
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| 180 | - jq in jq thread
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| 181 |
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| 182 | Old wiki pages:
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| 183 |
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| 184 | - <https://github.com/oilshell/oil/wiki/Structured-Data-in-Oil>
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| 185 | - uxy - closest I think - <https://github.com/sustrik/uxy>
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| 186 | - relies on to-json and jq for querying
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| 187 | - miller - I don't like their language - https://github.com/johnkerl/miller -
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| 188 | - jc - <https://github.com/kellyjonbrazil/jc>
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| 189 | - nushell
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| 190 | - extremely old thing -
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| 191 |
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| 192 | We're doing **all of these**.
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| 193 |
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| 194 | ## Concrete Use Cases
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| 195 |
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| 196 | - benchmarks/* with dplyr
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| 197 | - wedge report
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| 198 | - oilshell.org analytics job uses dplyr and ggplot2
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| 199 |
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| 200 | ## Intro
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| 201 |
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| 202 | ### How much code is it?
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| 203 |
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| 204 | - I think this is ~1000 lines of Python and ~1000 lines of YSH (not including tests)
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| 205 | - It should be small
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| 206 |
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| 207 | ### Thanks
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| 208 |
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| 209 | - Samuel - two big hints
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| 210 | - do it in YSH
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| 211 | - `table` with the `ctx` builtin
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| 212 | - Aidan
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| 213 | - `read --split` feedback
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| 214 |
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| 215 |
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| 216 | ## Tools
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| 217 |
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| 218 | - awk
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| 219 | - streams of records - row-wise
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| 220 | - R
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| 221 | - column-wise operations on tables
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| 222 | - `find . -printf '%s %P\n'` - size and path
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| 223 | - generate text that looks like a table
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| 224 | - xargs
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| 225 | - operate on tabular text -- it has a bespoke splitting algorithm
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| 226 | - Opinionated guide to xargs
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| 227 | - table in, table out
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| 228 | - jq - "awk for JSON"
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| 229 |
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| 230 |
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| 231 | ## Concepts
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| 232 |
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| 233 | - TSV8
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| 234 | - aligned format SSV8
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| 235 | - columns have types, and attributes
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| 236 | - Lines
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| 237 | - raw lines like shell
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| 238 | - J8 lines (which can represent any filename, any unicode or byte string)
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| 239 | - Tables - can be thought of as:
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| 240 | - Streams of Rows - shape `[{bytes: 123, path: "foo"}, {}, ...]`
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| 241 | - this is actually <https://jsonlines.org> , and it fits well with `jq`
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| 242 | - Columns - shape `{bytes: [], path: []}
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| 243 |
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| 244 | ## Underlying Mechanisms in Oils / Primitives
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| 245 |
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| 246 | - blocks `value.Block` - `^()` and `{ }`
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| 247 | - expressions `value.Expr` - `^[]` and 'compute [] where []'
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| 248 |
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| 249 | - eval (b, vars={}, positional=[])
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| 250 |
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| 251 | - Buffered for loop
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| 252 | - YSH is now roughly as fast as Awk!
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| 253 | - `for x in (io.stdin)`
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| 254 |
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| 255 | - "magic awk loop"
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| 256 |
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| 257 | with chop {
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| 258 | for <README.md *.py> {
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| 259 | echo _line_num _line _filename $1 $2
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| 260 | }
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| 261 | }
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| 262 |
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| 263 | - positional args $1 $2 $3
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| 264 | - currently mean "argv stack"
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| 265 | - or "the captures"
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| 266 | - this can probably be generalized
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| 267 |
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| 268 | - `ctx` builtin
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| 269 | - `value.Place`
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| 270 |
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| 271 | TODO:
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| 272 |
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| 273 | - split() like Python, not like shell IFS algorithm
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| 274 |
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| 275 | - string formatting ${bytes %.2f}
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| 276 | - ${bytes %.2f M} Megabytes
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| 277 | - ${bytes %.2f Mi} Mebibytes
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| 278 |
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| 279 | - ${timestamp +'%Y-m-%d'} and strfitime
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| 280 |
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| 281 | - this is for
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| 282 |
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| 283 | - floating point %e %f %g and printf and strftime
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| 284 |
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| 285 | ### Process Pool or Event Loop Primitive?
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| 286 |
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| 287 | - if you want to display progress, then you might need an event loop
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| 288 | - test framework might display progress
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| 289 |
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| 290 | ## Matrices - Orthogonal design in these dimensions
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| 291 |
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| 292 | - input: lines vs. rows
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| 293 | - output: string (Str, Template) vs. row vs. block execution (also a row)
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| 294 | - execution: serial vs. parallel
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| 295 | - representation: interior vs. exterior !!!
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| 296 | - Dicts and Lists are interior, but TSV8 is exterior
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| 297 | - and we have row-wise format, and column-wise format -- this always bugged me
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| 298 | - exterior: human vs. machine readable
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| 299 | - TSV8 is both human and machine-readable
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| 300 | - "aligned" #.ssv8 format is also
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| 301 | - they are one format named TSV8, with different file extensions. This is
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| 302 | because it doesn't make too much sense to implement SSV8 without TSV8. The
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| 303 | latter becomes trivial. So we call the whole thing TSV8.
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| 304 |
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| 305 | This means we consider all these conversions
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| 306 |
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| 307 | - Line -> Line
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| 308 | - Line -> Row
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| 309 | - Row -> Line
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| 310 | - Row -> Row
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| 311 |
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| 312 | ## Concrete Decisions - Matrix cut off
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| 313 |
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| 314 | Design might seem very general, but we did make some hard choices.
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| 315 |
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| 316 | - push vs. pull
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| 317 | - everything is "push" style I think
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| 318 | - buffered vs. unbuffered, everything
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| 319 |
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| 320 | - List vs iterators
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| 321 | - everything is either iterable pipelines, or a List
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| 322 |
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| 323 |
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| 324 | [OSH]: $xref
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| 325 | [YSH]: $xref
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| 326 |
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| 327 |
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| 328 | ## String World
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| 329 |
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| 330 | **THESE ARE ALL THE SAME ALGORITHM**. They just have different names.
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| 331 |
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| 332 | - each-line
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| 333 | - each-row
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| 334 | - split-by (/d+/, cols=:|a b c|)
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| 335 | - chop
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| 336 | - if-match
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| 337 | - must-match
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| 338 | - todo
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| 339 |
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| 340 | should we also have: if-split-by ? In case there aren't enough columns?
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| 341 |
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| 342 | They all take:
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| 343 |
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| 344 | - string arg ' '
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| 345 | - template arg (^"") - `value.Expr`
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| 346 | - block arg
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| 347 |
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| 348 | for the block arg, this applies:
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| 349 |
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| 350 | -j 4
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| 351 | --max-jobs 4
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| 352 |
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| 353 | --max-jobs $(cached-nproc)
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| 354 | --max-jobs $[_nproc - 1]
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| 355 |
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| 356 | ### Awk Issues
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| 357 |
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| 358 | So we have this
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| 359 |
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| 360 | echo begin
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| 361 | var d = {}
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| 362 | cat -- @files | split-by (ifs=IFS) {
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| 363 | echo $2 $1
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| 364 | call d->accum($1, $2)
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| 365 | }
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| 366 | echo end
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| 367 |
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| 368 | But then how do we have conditionals:
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| 369 |
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| 370 | Filter foo { # does this define a proc? Or a data structure
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| 371 |
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| 372 | split-by (ifs=IFS) # is this possible? We register the proc itself?
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| 373 |
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| 374 | config split-by (ifs=IFS) # register it
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| 375 |
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| 376 | BEGIN {
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| 377 | var d = {}
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| 378 | }
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| 379 | END {
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| 380 | echo d.sum
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| 381 | }
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| 382 |
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| 383 | when [$1 ~ /d+/] {
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| 384 | setvar d.sum += $1
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| 385 | }
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| 386 |
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| 387 | }
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| 388 |
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| 389 | ## Table World
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| 390 |
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| 391 | ### `table` to construct
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| 392 |
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| 393 | Actions:
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| 394 |
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| 395 | table cat
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| 396 | table align / table tabify
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| 397 | table header (cols)
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| 398 | table slice (1, -1) or (-1, -2) etc.
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| 399 |
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| 400 | Subcommands
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| 401 |
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| 402 | cols
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| 403 | types
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| 404 | attr units
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| 405 |
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| 406 | Partial Parsing / Lazy Parsing - TSV8 is designed for this
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| 407 |
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| 408 | # we only decode the columns that are necessary
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| 409 | cat myfile.tsv8 | table --by-col (&out, cols = :|bytes path|)
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| 410 |
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| 411 | ## Will writing it in YSH be slow?
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| 412 |
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| 413 | - We concentrate on semantics first
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| 414 | - We can rewrite in Python
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| 415 | - Better: users can use **exterior** tools with the same interface
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| 416 | - in some cases
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| 417 | - they can write an efficient `sort-tsv8` or `join-tsv8` with novel algorithms
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| 418 | - Most data will be small at first
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| 419 |
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| 420 |
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| 421 | ## Applications
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| 422 |
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| 423 | - Shell is shared nothing
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| 424 | - Scaling to infinity on the biggest clouds
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| 425 |
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| 426 |
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| 427 | ## Extra: Tree World?
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| 428 |
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| 429 | This is sort of "expanding the scope" of the project, when we want to reduce scope.
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| 430 |
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| 431 | But YSH has both tree-shaped JSON, and table-shaped TSV8, and jq is a nice **bridge** between them.
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| 432 |
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| 433 | Streams of Trees (jq)
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| 434 |
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| 435 | empty
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| 436 | this
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| 437 | this[]
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| 438 | =>
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| 439 | select()
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| 440 | a & b # more than one
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| 441 |
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| 442 |
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| 443 | ## Pie in the Sky
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| 444 |
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| 445 | Four types of Data Languages:
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| 446 |
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| 447 | - flat strings
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| 448 | - JSON8 - tree
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| 449 | - TSV8 - table
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| 450 | - NIL8 - Lisp Tree
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| 451 | - HTML/XML - doc tree -- attributed text (similar to Emacs data model)
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| 452 | - 8ml
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| 453 |
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| 454 | Four types of query languaegs:
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| 455 |
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| 456 | - regex
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| 457 | - jq / jshape
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| 458 | - tsv8
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| 459 |
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| 460 |
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| 461 | ## Appendix
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| 462 |
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| 463 | ### Notes on Naming
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| 464 |
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| 465 | Considering columns and then rows:
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| 466 |
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| 467 | - SQL is "select ... where"
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| 468 | - dplyr is "select ... filter"
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| 469 | - YSH is "pick ... where"
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| 470 | - select is a legacy shell keyword, and pick is shorter
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| 471 | - or it could be elect in OSH, elect/select in YSH
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| 472 | - OSH wouldn't support mutate [average = bytes/total] anyway
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| 473 |
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| 474 | dplyr:
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| 475 |
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| 476 | - summarise vs. summarize vs. summary
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| 477 |
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| 478 |
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| 479 |
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| 480 |
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| 481 |
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