application/octet-stream
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3.09 KB
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96 lines
; Mostly macros implementing different control flow constructs
[defmacro if-not [pred then else]
`[if ~pred ~else ~then]
]
[defmacro if-let [binding then else]
`[let* [def ~[car binding] ~[cadr binding]]
[if ~[car binding] ~then ~else]
]
]
[defmacro when-let [binding ...body]
`[if-let ~binding ~[cons 'do ...body] #nil]
]
[defmacro when-not [pred ...body]
"Evalutes to BODY if PRED is false"
`[if ~pred #nil [do ~@...body]]
]
[defmacro when [pred ...body]
"Evalutes to BODY if PRED is true"
`[if ~pred [do ~@...body] #nil]
]
[defun let/arg [arg]
[when-not [pair? arg] [throw `[:invalid-let-form "Please fix the structure of the let form" ~arg]]]
[when-not [symbol? [car arg]] [throw `[:invalid-let-form "Please fix the structure of the let form" ~arg]]]
`[def ~[car arg] ~[cadr arg]]
]
[defun let/args [args]
[if args
[cons [let/arg [car args]]
[let/args [cdr args]]]
#nil]
]
[defmacro let [bindings ...body]
"Evalutes to BODY if PRED is true"
`[let* [do ~@[let/args bindings] ~@...body]]
]
[defun case/clauses/multiple [key-sym cases]
[when cases
[cons [list '== key-sym [car cases]]
[case/clauses/multiple key-sym [cdr cases]]]]
]
[defun case/clauses [key-sym clauses]
[when clauses
[if [== [caar clauses] 'otherwise]
[cons 'do [cdar clauses]]
[list 'if
[if [pair? [caar clauses]]
[cons 'or [case/clauses/multiple key-sym [caar clauses]]]
[list '== key-sym [caar clauses]]]
[cons 'do [cdar clauses]]
[case/clauses key-sym [cdr clauses]]]]]
]
[defmacro case [key-form ...clauses]
[def key-sym [gensym]]
[list 'let*
[list 'def key-sym key-form]
[case/clauses key-sym ...clauses]]
]
[defmacro cond [...body]
"Contains multiple cond clauses"
[when ...body
[list 'if
[caar ...body]
[cons 'do [cdar ...body]]
[macro-apply cond [cdr ...body]]]]
]
[defmacro for [for-loop ...body]
"For loops, [for [name start stop] ...body]"
[def symbol-name [car for-loop]]
[def loop-start [cadr for-loop]]
[def loop-stop [caddr for-loop]]
[def dir 1]
[when [cadddr for-loop] [set! dir [cadddr for-loop]]]
[when-not [symbol? symbol-name]
[throw [list :invalid-for "Expected a symbol name within the for loop" symbol-name]]]
[when-not loop-start
[throw [list :invalid-for "Expected a start value at the second position" for-loop]]]
[when-not loop-stop
[throw [list :invalid-for "Expected a stop value at the third position" for-loop]]]
`[let [[~symbol-name ~loop-start]]
[while [!= ~symbol-name ~loop-stop]
~@...body
[set! ~symbol-name [+ ~dir ~symbol-name]]
]
]
]
