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<pre id='vimCodeElement'>
<span class="SalientComment">## experimental compiler to translate programs written in a generic</span>
<span class="SalientComment">## expression-oriented language called 'lambda' into Mu</span>

<span class="muScenario">scenario</span> convert-lambda [
  run [
    <span class="Constant">local-scope</span>
    1:text/<span class="Special">raw</span> <span class="Special">&lt;-</span> lambda-to-mu <span class="Constant">[(add a (multiply b c))]</span>
    2:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *1:text/<span class="Special">raw</span>
  ]
  memory-should-contain [
    2:array:character <span class="Special">&lt;-</span> <span class="Constant">[t1 &lt;- multiply b c</span>
<span class="Constant">result &lt;- add a t1]</span>
  ]
]

<span class="muRecipe">def</span> lambda-to-mu in:text<span class="muRecipe"> -&gt; </span>out:text [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  out <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
  cells:&amp;:cell <span class="Special">&lt;-</span> parse in
  out <span class="Special">&lt;-</span> to-mu cells
]

<span class="Comment"># 'parse' will turn lambda expressions into trees made of cells</span>
<span class="muData">exclusive-container</span> cell [
  atom:text
  pair:pair
]

<span class="Comment"># printed below as &lt; first | rest &gt;</span>
<span class="muData">container</span> pair [
  first:&amp;:cell
  rest:&amp;:cell
]

<span class="muRecipe">def</span> new-atom name:text<span class="muRecipe"> -&gt; </span>result:&amp;:cell [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  result <span class="Special">&lt;-</span> new <span class="Constant">cell:type</span>
  *result <span class="Special">&lt;-</span> merge <span class="Constant">0/tag:atom</span>, name
]

<span class="muRecipe">def</span> new-pair a:&amp;:cell, b:&amp;:cell<span class="muRecipe"> -&gt; </span>result:&amp;:cell [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  result <span class="Special">&lt;-</span> new <span class="Constant">cell:type</span>
  *result <span class="Special">&lt;-</span> merge <span class="Constant">1/tag:pair</span>, a/first, b/rest
]

<span class="muRecipe">def</span> is-atom? x:&amp;:cell<span class="muRecipe"> -&gt; </span>result:bool [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="muControl">return-unless</span> x, <span class="Constant">0/false</span>
  _, result <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">atom:variant</span>
]

<span class="muRecipe">def</span> is-pair? x:&amp;:cell<span class="muRecipe"> -&gt; </span>result:bool [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="muControl">return-unless</span> x, <span class="Constant">0/false</span>
  _, result <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">pair:variant</span>
]

<span class="muScenario">scenario</span> atom-is-not-pair [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[a]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> new-atom s
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-atom? x
  11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>
  ]
]

<span class="muScenario">scenario</span> pair-is-not-atom [
  <span class="Constant">local-scope</span>
  <span class="Comment"># construct (a . nil)</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[a]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> new-atom s
  y:&amp;:cell <span class="Special">&lt;-</span> new-pair x, <span class="Constant">0/nil</span>
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-atom? y
  11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? y
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>
  ]
]

<span class="muRecipe">def</span> atom-match? x:&amp;:cell, pat:text<span class="muRecipe"> -&gt; </span>result:bool [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  s:text, is-atom?:bool <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">atom:variant</span>
  <span class="muControl">return-unless</span> is-atom?, <span class="Constant">0/false</span>
  result <span class="Special">&lt;-</span> equal pat, s
]

<span class="muScenario">scenario</span> atom-match [
  <span class="Constant">local-scope</span>
  x:&amp;:cell <span class="Special">&lt;-</span> new-atom <span class="Constant">[abc]</span>
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> atom-match? x, <span class="Constant">[abc]</span>
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>
  ]
]

<span class="muRecipe">def</span> first x:&amp;:cell<span class="muRecipe"> -&gt; </span>result:&amp;:cell [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  pair:pair, pair?:bool <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">pair:variant</span>
  <span class="muControl">return-unless</span> pair?, <span class="Constant">0/nil</span>
  result <span class="Special">&lt;-</span> get pair, <span class="Constant">first:offset</span>
]

<span class="muRecipe">def</span> rest x:&amp;:cell<span class="muRecipe"> -&gt; </span>result:&amp;:cell [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  pair:pair, pair?:bool <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">pair:variant</span>
  <span class="muControl">return-unless</span> pair?, <span class="Constant">0/nil</span>
  result <span class="Special">&lt;-</span> get pair, <span class="Constant">rest:offset</span>
]

<span class="muRecipe">def</span> set-first base:&amp;:cell, new-first:&amp;:cell<span class="muRecipe"> -&gt; </span>base:&amp;:cell [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  pair:pair, is-pair?:bool <span class="Special">&lt;-</span> maybe-convert *base, <span class="Constant">pair:variant</span>
  <span class="muControl">return-unless</span> is-pair?
  pair <span class="Special">&lt;-</span> put pair, <span class="Constant">first:offset</span>, new-first
  *base <span class="Special">&lt;-</span> merge <span class="Constant">1/pair</span>, pair
]

<span class="muRecipe">def</span> set-rest base:&amp;:cell, new-rest:&amp;:cell<span class="muRecipe"> -&gt; </span>base:&amp;:cell [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  pair:pair, is-pair?:bool <span class="Special">&lt;-</span> maybe-convert *base, <span class="Constant">pair:variant</span>
  <span class="muControl">return-unless</span> is-pair?
  pair <span class="Special">&lt;-</span> put pair, <span class="Constant">rest:offset</span>, new-rest
  *base <span class="Special">&lt;-</span> merge <span class="Constant">1/pair</span>, pair
]

<span class="muScenario">scenario</span> cell-operations-on-atom [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[a]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> new-atom s
  10:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> first x
  11:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># first is nil</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># rest is nil</span>
  ]
]

<span class="muScenario">scenario</span> cell-operations-on-pair [
  <span class="Constant">local-scope</span>
  <span class="Comment"># construct (a . nil)</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[a]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> new-atom s
  y:&amp;:cell <span class="Special">&lt;-</span> new-pair x, <span class="Constant">0/nil</span>
  x2:&amp;:cell <span class="Special">&lt;-</span> first y
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> equal x, x2
  11:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest y
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># first is correct</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># rest is nil</span>
  ]
]

<span class="SalientComment">## convert lambda text to a tree of cells</span>

<span class="muRecipe">def</span> parse in:text<span class="muRecipe"> -&gt; </span>out:&amp;:cell [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  s:&amp;:stream:char <span class="Special">&lt;-</span> new-stream in
  out, s <span class="Special">&lt;-</span> parse s
  trace<span class="Constant"> 2</span>, <span class="Constant">[app/parse]</span>, out
]

<span class="muRecipe">def</span> parse in:&amp;:stream:char<span class="muRecipe"> -&gt; </span>out:&amp;:cell, in:&amp;:stream:char [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Comment"># skip whitespace</span>
  in <span class="Special">&lt;-</span> skip-whitespace in
  c:char, eof?:bool <span class="Special">&lt;-</span> peek in
  <span class="muControl">return-if</span> eof?, <span class="Constant">0/nil</span>
  pair?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">40/open-paren</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-if</span> pair?
    <span class="Comment"># atom</span>
    buf:&amp;:buffer <span class="Special">&lt;-</span> new-buffer<span class="Constant"> 30</span>
    <span class="Delimiter">{</span>
      done?:bool <span class="Special">&lt;-</span> end-of-stream? in
      <span class="muControl">break-if</span> done?
      <span class="Comment"># stop before close paren or space</span>
      c:char <span class="Special">&lt;-</span> peek in
      done? <span class="Special">&lt;-</span> equal c, <span class="Constant">41/close-paren</span>
      <span class="muControl">break-if</span> done?
      done? <span class="Special">&lt;-</span> space? c
      <span class="muControl">break-if</span> done?
      c <span class="Special">&lt;-</span> read in
      buf <span class="Special">&lt;-</span> append buf, c
      <span class="muControl">loop</span>
    <span class="Delimiter">}</span>
    s:text <span class="Special">&lt;-</span> buffer-to-array buf
    out <span class="Special">&lt;-</span> new-atom s
  <span class="Delimiter">}</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> pair?
    <span class="Comment"># pair</span>
    read in  <span class="Comment"># skip the open-paren</span>
    out <span class="Special">&lt;-</span> new <span class="Constant">cell:type</span>  <span class="Comment"># start out with nil</span>
    <span class="Comment"># read in first element of pair</span>
    <span class="Delimiter">{</span>
      end?:bool <span class="Special">&lt;-</span> end-of-stream? in
      not-end?:bool <span class="Special">&lt;-</span> not end?
      assert not-end?, <span class="Constant">[unbalanced '(' in expression]</span>
      c <span class="Special">&lt;-</span> peek in
      close-paren?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">41/close-paren</span>
      <span class="muControl">break-if</span> close-paren?
      first:&amp;:cell, in <span class="Special">&lt;-</span> parse in
      *out <span class="Special">&lt;-</span> merge <span class="Constant">1/pair</span>, first, <span class="Constant">0/nil</span>
    <span class="Delimiter">}</span>
    <span class="Comment"># read in any remaining elements</span>
    curr:&amp;:cell <span class="Special">&lt;-</span> copy out
    <span class="Delimiter">{</span>
      in <span class="Special">&lt;-</span> skip-whitespace in
      end?:bool <span class="Special">&lt;-</span> end-of-stream? in
      not-end?:bool <span class="Special">&lt;-</span> not end?
      assert not-end?, <span class="Constant">[unbalanced '(' in expression]</span>
      <span class="Comment"># termination check: ')'</span>
      c <span class="Special">&lt;-</span> peek in
      <span class="Delimiter">{</span>
        close-paren?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">41/close-paren</span>
        <span class="muControl">break-unless</span> close-paren?
        read in  <span class="Comment"># skip ')'</span>
        <span class="muControl">break</span> <span class="Constant">+end-pair</span>
      <span class="Delimiter">}</span>
      <span class="Comment"># still here? read next element of pair</span>
      next:&amp;:cell, in <span class="Special">&lt;-</span> parse in
      is-dot?:bool <span class="Special">&lt;-</span> atom-match? next, <span class="Constant">[.]</span>
      <span class="Delimiter">{</span>
        <span class="muControl">break-if</span> is-dot?
        next-curr:&amp;:cell <span class="Special">&lt;-</span> new-pair next, <span class="Constant">0/nil</span>
        curr <span class="Special">&lt;-</span> set-rest curr, next-curr
        curr <span class="Special">&lt;-</span> rest curr
      <span class="Delimiter">}</span>
      <span class="Delimiter">{</span>
        <span class="muControl">break-unless</span> is-dot?
        <span class="Comment"># deal with dotted pair</span>
        in <span class="Special">&lt;-</span> skip-whitespace in
        c <span class="Special">&lt;-</span> peek in
        not-close-paren?:bool <span class="Special">&lt;-</span> not-equal c, <span class="Constant">41/close-paren</span>
        assert not-close-paren?, <span class="Constant">[')' cannot immediately follow '.']</span>
        final:&amp;:cell <span class="Special">&lt;-</span> parse in
        curr <span class="Special">&lt;-</span> set-rest curr, final
        <span class="Comment"># we're not gonna update curr, so better make sure the next iteration</span>
        <span class="Comment"># is going to end the pair</span>
        in <span class="Special">&lt;-</span> skip-whitespace in
        c <span class="Special">&lt;-</span> peek in
        close-paren?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">41/close-paren</span>
        assert close-paren?, <span class="Constant">['.' must be followed by exactly one expression before ')']</span>
      <span class="Delimiter">}</span>
      <span class="muControl">loop</span>
    <span class="Delimiter">}</span>
<span class="Constant">    +end-pair</span>
  <span class="Delimiter">}</span>
]

<span class="muRecipe">def</span> skip-whitespace in:&amp;:stream:char<span class="muRecipe"> -&gt; </span>in:&amp;:stream:char [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Delimiter">{</span>
    done?:bool <span class="Special">&lt;-</span> end-of-stream? in
    <span class="muControl">return-if</span> done?, <span class="Constant">0/null</span>
    c:char <span class="Special">&lt;-</span> peek in
    space?:bool <span class="Special">&lt;-</span> space? c
    <span class="muControl">break-unless</span> space?
    read in  <span class="Comment"># skip</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
]

<span class="muRecipe">def</span> to-text x:&amp;:cell<span class="muRecipe"> -&gt; </span>out:text [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  buf:&amp;:buffer <span class="Special">&lt;-</span> new-buffer<span class="Constant"> 30</span>
  buf <span class="Special">&lt;-</span> to-buffer x, buf
  out <span class="Special">&lt;-</span> buffer-to-array buf
]

<span class="muRecipe">def</span> to-buffer x:&amp;:cell, buf:&amp;:buffer<span class="muRecipe"> -&gt; </span>buf:&amp;:buffer [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Comment"># base case: empty cell</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-if</span> x
    buf <span class="Special">&lt;-</span> append buf, <span class="Constant">[&lt;&gt;]</span>
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># base case: atom</span>
  <span class="Delimiter">{</span>
    s:text, atom?:bool <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">atom:variant</span>
    <span class="muControl">break-unless</span> atom?
    buf <span class="Special">&lt;-</span> append buf, s
    <span class="muControl">return</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># recursive case: pair</span>
  buf <span class="Special">&lt;-</span> append buf, <span class="Constant">[&lt; ]</span>
  first:&amp;:cell <span class="Special">&lt;-</span> first x
  buf <span class="Special">&lt;-</span> to-buffer first, buf
  buf <span class="Special">&lt;-</span> append buf, <span class="Constant">[ | ]</span>
  rest:&amp;:cell <span class="Special">&lt;-</span> rest x
  buf <span class="Special">&lt;-</span> to-buffer rest, buf
  buf <span class="Special">&lt;-</span> append buf, <span class="Constant">[ &gt;]</span>
]

<span class="muScenario">scenario</span> parse-single-letter-atom [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[a]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  s2:text, 10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">atom:variant</span>
  11:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is an atom</span>
    11:array:character <span class="Special">&lt;-</span> <span class="Constant">[a]</span>
  ]
]

<span class="muScenario">scenario</span> parse-atom [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[abc]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  s2:text, 10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x, <span class="Constant">atom:variant</span>
  11:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is an atom</span>
    11:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>
  ]
]

<span class="muScenario">scenario</span> parse-list-of-two-atoms [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[(abc def)]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  trace-should-contain [
    app/parse: <span class="Constant">&lt;</span> abc <span class="Constant">|</span> <span class="Constant">&lt;</span> def <span class="Constant">|</span> <span class="Constant">&lt;&gt;</span> <span class="Constant">&gt;</span> <span class="Constant">&gt;</span>
  ]
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x1:&amp;:cell <span class="Special">&lt;-</span> first x
  x2:&amp;:cell <span class="Special">&lt;-</span> rest x
  s1:text, 11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x1, <span class="Constant">atom:variant</span>
  12:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x2
  x3:&amp;:cell <span class="Special">&lt;-</span> first x2
  s2:text, 13:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x3, <span class="Constant">atom:variant</span>
  14:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x2
  20:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s1
  30:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is a pair</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first is an atom</span>
   <span class="Constant"> 12</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest is a pair</span>
   <span class="Constant"> 13</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.first is an atom</span>
   <span class="Constant"> 14</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># result.rest.rest is nil</span>
    20:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>  <span class="Comment"># result.first</span>
    30:array:character <span class="Special">&lt;-</span> <span class="Constant">[def]</span>  <span class="Comment"># result.rest.first</span>
  ]
]

<span class="muScenario">scenario</span> parse-list-with-extra-spaces [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[ ( abc  def ) ]</span>  <span class="Comment"># extra spaces</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  trace-should-contain [
    app/parse: <span class="Constant">&lt;</span> abc <span class="Constant">|</span> <span class="Constant">&lt;</span> def <span class="Constant">|</span> <span class="Constant">&lt;&gt;</span> <span class="Constant">&gt;</span> <span class="Constant">&gt;</span>
  ]
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x1:&amp;:cell <span class="Special">&lt;-</span> first x
  x2:&amp;:cell <span class="Special">&lt;-</span> rest x
  s1:text, 11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x1, <span class="Constant">atom:variant</span>
  12:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x2
  x3:&amp;:cell <span class="Special">&lt;-</span> first x2
  s2:text, 13:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x3, <span class="Constant">atom:variant</span>
  14:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x2
  20:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s1
  30:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is a pair</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first is an atom</span>
   <span class="Constant"> 12</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest is a pair</span>
   <span class="Constant"> 13</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.first is an atom</span>
   <span class="Constant"> 14</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># result.rest.rest is nil</span>
    20:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>  <span class="Comment"># result.first</span>
    30:array:character <span class="Special">&lt;-</span> <span class="Constant">[def]</span>  <span class="Comment"># result.rest.first</span>
  ]
]

<span class="muScenario">scenario</span> parse-list-of-more-than-two-atoms [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[(abc def ghi)]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  trace-should-contain [
    app/parse: <span class="Constant">&lt;</span> abc <span class="Constant">|</span> <span class="Constant">&lt;</span> def <span class="Constant">|</span> <span class="Constant">&lt;</span> ghi <span class="Constant">|</span> <span class="Constant">&lt;&gt;</span> <span class="Constant">&gt;</span> <span class="Constant">&gt;</span> <span class="Constant">&gt;</span>
  ]
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x1:&amp;:cell <span class="Special">&lt;-</span> first x
  x2:&amp;:cell <span class="Special">&lt;-</span> rest x
  s1:text, 11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x1, <span class="Constant">atom:variant</span>
  12:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x2
  x3:&amp;:cell <span class="Special">&lt;-</span> first x2
  s2:text, 13:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x3, <span class="Constant">atom:variant</span>
  x4:&amp;:cell <span class="Special">&lt;-</span> rest x2
  14:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x4
  x5:&amp;:cell <span class="Special">&lt;-</span> first x4
  s3:text, 15:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x5, <span class="Constant">atom:variant</span>
  16:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x4
  20:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s1
  30:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  40:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s3
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is a pair</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first is an atom</span>
   <span class="Constant"> 12</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest is a pair</span>
   <span class="Constant"> 13</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.first is an atom</span>
   <span class="Constant"> 14</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.rest is a pair</span>
   <span class="Constant"> 15</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.rest.first is an atom</span>
   <span class="Constant"> 16</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># result.rest.rest.rest is nil</span>
    20:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>  <span class="Comment"># result.first</span>
    30:array:character <span class="Special">&lt;-</span> <span class="Constant">[def]</span>  <span class="Comment"># result.rest.first</span>
    40:array:character <span class="Special">&lt;-</span> <span class="Constant">[ghi]</span>  <span class="Comment"># result.rest.rest</span>
  ]
]

<span class="muScenario">scenario</span> parse-nested-list [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[((abc))]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  trace-should-contain [
    app/parse: <span class="Constant">&lt;</span> <span class="Constant">&lt;</span> abc <span class="Constant">|</span> <span class="Constant">&lt;&gt;</span> <span class="Constant">&gt;</span> <span class="Constant">|</span> <span class="Constant">&lt;&gt;</span> <span class="Constant">&gt;</span>
  ]
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x1:&amp;:cell <span class="Special">&lt;-</span> first x
  11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x2:&amp;:cell <span class="Special">&lt;-</span> first x1
  s1:text, 12:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x2, <span class="Constant">atom:variant</span>
  13:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x1
  14:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x
  20:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s1
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is a pair</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first is a pair</span>
   <span class="Constant"> 12</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first.first is an atom</span>
   <span class="Constant"> 13</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># result.first.rest is nil</span>
   <span class="Constant"> 14</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># result.rest is nil</span>
    20:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>  <span class="Comment"># result.first.first</span>
  ]
]

<span class="muScenario">scenario</span> parse-nested-list-2 [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[((abc) def)]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  trace-should-contain [
    app/parse: <span class="Constant">&lt;</span> <span class="Constant">&lt;</span> abc <span class="Constant">|</span> <span class="Constant">&lt;&gt;</span> <span class="Constant">&gt;</span> <span class="Constant">|</span> <span class="Constant">&lt;</span> def <span class="Constant">|</span> <span class="Constant">&lt;&gt;</span> <span class="Constant">&gt;</span> <span class="Constant">&gt;</span>
  ]
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x1:&amp;:cell <span class="Special">&lt;-</span> first x
  11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x2:&amp;:cell <span class="Special">&lt;-</span> first x1
  s1:text, 12:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x2, <span class="Constant">atom:variant</span>
  13:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x1
  x3:&amp;:cell <span class="Special">&lt;-</span> rest x
  x4:&amp;:cell <span class="Special">&lt;-</span> first x3
  s2:text, 14:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x4, <span class="Constant">atom:variant</span>
  15:&amp;:cell/<span class="Special">raw</span> <span class="Special">&lt;-</span> rest x3
  20:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s1
  30:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is a pair</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first is a pair</span>
   <span class="Constant"> 12</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first.first is an atom</span>
   <span class="Constant"> 13</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># result.first.rest is nil</span>
   <span class="Constant"> 14</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.first is an atom</span>
   <span class="Constant"> 15</span> <span class="Special">&lt;-</span><span class="Constant"> 0</span>  <span class="Comment"># result.rest.rest is nil</span>
    20:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>  <span class="Comment"># result.first.first</span>
    30:array:character <span class="Special">&lt;-</span> <span class="Constant">[def]</span>  <span class="Comment"># result.rest.first</span>
  ]
]

<span class="Comment"># todo: uncomment these tests after we figure out how to continue tests after</span>
<span class="Comment"># assertion failures</span>
<span class="CommentedCode">#? scenario parse-error [</span>
<span class="CommentedCode">#?   local-scope</span>
<span class="CommentedCode">#?   s:text &lt;- new [(]</span>
<span class="CommentedCode">#? #?   hide-errors</span>
<span class="CommentedCode">#?   x:&amp;:cell &lt;- parse s</span>
<span class="CommentedCode">#? #?   show-errors</span>
<span class="CommentedCode">#?   trace-should-contain [</span>
<span class="CommentedCode">#?     error: unbalanced '(' in expression</span>
<span class="CommentedCode">#?   ]</span>
<span class="CommentedCode">#? ]</span>
<span class="CommentedCode">#? </span>
<span class="CommentedCode">#? scenario parse-error-after-element [</span>
<span class="CommentedCode">#?   local-scope</span>
<span class="CommentedCode">#?   s:text &lt;- new [(abc]</span>
<span class="CommentedCode">#? #?   hide-errors</span>
<span class="CommentedCode">#?   x:&amp;:cell &lt;- parse s</span>
<span class="CommentedCode">#? #?   show-errors</span>
<span class="CommentedCode">#?   trace-should-contain [</span>
<span class="CommentedCode">#?     error: unbalanced '(' in expression</span>
<span class="CommentedCode">#?   ]</span>
<span class="CommentedCode">#? ]</span>

<span class="muScenario">scenario</span> parse-dotted-list-of-two-atoms [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[(abc . def)]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  trace-should-contain [
    app/parse: <span class="Constant">&lt;</span> abc <span class="Constant">|</span> def <span class="Constant">&gt;</span>
  ]
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x1:&amp;:cell <span class="Special">&lt;-</span> first x
  x2:&amp;:cell <span class="Special">&lt;-</span> rest x
  s1:text, 11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x1, <span class="Constant">atom:variant</span>
  s2:text, 12:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x2, <span class="Constant">atom:variant</span>
  20:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s1
  30:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  memory-should-contain [
    <span class="Comment"># parses to &lt; abc | def &gt;</span>
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is a pair</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first is an atom</span>
   <span class="Constant"> 12</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest is an atom</span>
    20:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>  <span class="Comment"># result.first</span>
    30:array:character <span class="Special">&lt;-</span> <span class="Constant">[def]</span>  <span class="Comment"># result.rest</span>
  ]
]

<span class="muScenario">scenario</span> parse-dotted-list-of-more-than-two-atoms [
  <span class="Constant">local-scope</span>
  s:text <span class="Special">&lt;-</span> new <span class="Constant">[(abc def . ghi)]</span>
  x:&amp;:cell <span class="Special">&lt;-</span> parse s
  trace-should-contain [
    app/parse: <span class="Constant">&lt;</span> abc <span class="Constant">|</span> <span class="Constant">&lt;</span> def <span class="Constant">|</span> ghi <span class="Constant">&gt;</span> <span class="Constant">&gt;</span>
  ]
  10:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x
  x1:&amp;:cell <span class="Special">&lt;-</span> first x
  x2:&amp;:cell <span class="Special">&lt;-</span> rest x
  s1:text, 11:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x1, <span class="Constant">atom:variant</span>
  12:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> is-pair? x2
  x3:&amp;:cell <span class="Special">&lt;-</span> first x2
  s2:text, 13:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x3, <span class="Constant">atom:variant</span>
  x4:&amp;:cell <span class="Special">&lt;-</span> rest x2
  s3:text, 14:bool/<span class="Special">raw</span> <span class="Special">&lt;-</span> maybe-convert *x4, <span class="Constant">atom:variant</span>
  20:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s1
  30:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s2
  40:@:char/<span class="Special">raw</span> <span class="Special">&lt;-</span> copy *s3
  memory-should-contain [
   <span class="Constant"> 10</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># parse result is a pair</span>
   <span class="Constant"> 11</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.first is an atom</span>
   <span class="Constant"> 12</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest is a pair</span>
   <span class="Constant"> 13</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.first is an atom</span>
   <span class="Constant"> 14</span> <span class="Special">&lt;-</span><span class="Constant"> 1</span>  <span class="Comment"># result.rest.rest is an atom</span>
    20:array:character <span class="Special">&lt;-</span> <span class="Constant">[abc]</span>  <span class="Comment"># result.first</span>
    30:array:character <span class="Special">&lt;-</span> <span class="Constant">[def]</span>  <span class="Comment"># result.rest.first</span>
    40:array:character <span class="Special">&lt;-</span> <span class="Constant">[ghi]</span>  <span class="Comment"># result.rest.rest</span>
  ]
]

<span class="SalientComment">## convert tree of cells to Mu text</span>

<span class="muRecipe">def</span> to-mu in:&amp;:cell<span class="muRecipe"> -&gt; </span>out:text [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  buf:&amp;:buffer <span class="Special">&lt;-</span> new-buffer<span class="Constant"> 30</span>
  buf <span class="Special">&lt;-</span> to-mu in, buf
  out <span class="Special">&lt;-</span> buffer-to-array buf
]

<span class="muRecipe">def</span> to-mu in:&amp;:cell, buf:&amp;:buffer<span class="muRecipe"> -&gt; </span>buf:&amp;:buffer, result-name:text [
  <span class="Constant">local-scope</span>
  <span class="Constant">load-ingredients</span>
  <span class="Comment"># null cell? no change.</span>
  <span class="Comment"># pair with all atoms? gensym a new variable</span>
  <span class="Comment"># pair containing other pairs? recurse</span>
  result-name <span class="Special">&lt;-</span> copy<span class="Constant"> 0</span>
]
</pre>
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