init parser

.gitignore

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+.dub
+docs.json
+__dummy.html
+docs/
+/scheme-d
+scheme-d.so
+scheme-d.dylib
+scheme-d.dll
+scheme-d.a
+scheme-d.lib
+scheme-d-test-*
+*.exe
+*.o
+*.obj
+*.lst

dub.json

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+{
+    "authors": [
+        "karita"
+    ],
+    "copyright": "Copyright © 2019, karita",
+    "dependencies": {
+        "pegged": "~>0.4.4",
+        "sumtype": "~>0.9.4"
+    },
+    "description": "Write yourself a Scheme in 48 Hours in D",
+    "license": "BSL-1.0",
+    "name": "scheme-d"
+}

dub.selections.json

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+{
+	"fileVersion": 1,
+	"versions": {
+		"pegged": "0.4.4",
+		"sumtype": "0.9.4"
+	}
+}

source/app.d

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+import std.stdio;
+import std.typecons;
+
+import sumtype;
+import pegged.grammar;
+
+
+mixin(grammar(`
+SchemeParser:
+    Body < SExpr* / Comment
+    Comment <: ';' (!endOfLine .)* endOfLine
+    SExpr < :'(' (Value / Comment)* :')'
+    Value < Number / List / Atom / String / True / False / SExpr
+    List < quote SExpr
+
+    Atom <~ AtomChar (AtomChar / Digit)*
+    AtomChar <- [a-zA-Z_] / '+' / '-' / '*' / '/'
+              / quote / ':' / '!' / '$' / '%' / '&' / '=' / '~' / '^' / ':'
+    String <~ :doublequote Char* :doublequote
+    Char   <~ backslash doublequote
+            / backslash backslash
+            / backslash [bfnrt]
+            / (!doublequote .)
+
+    Number <~ '-'? ('0' / [1-9] Digit* ('.' Digit*)?)
+    Digit  <- [0-9]
+
+    True <- "#t"
+    False <- "#f"
+`));
+
+struct Atom { string name; }
+struct List { Object[] data; }
+struct DottedList
+{
+    Object[] data;
+    Object tail;
+}
+
+alias Object = SumType!(
+    Atom,
+    List,
+    long,
+    string,
+    bool);
+
+void main(string[] args)
+{
+    enum input1 = `
+(f0 #t #f '(1 2 3) '())
+
+(f1 "string"
+    ;; comment
+    (+ 20 -30))
+`;
+    writeln(SchemeParser(input1));
+    // writeln("Hello, ", args[1]);
+}