diff options
| -rw-r--r-- | README.md | 3 | ||||
| -rw-r--r-- | interpreter.py | 35 |
2 files changed, 38 insertions, 0 deletions
@@ -42,9 +42,11 @@ - `(/ [num :number] [denom :number]) => :number` ### string + - `(first-char [arg :string]) => :string` - `(concat [arg :string] [many :string]) => :string` - `(join [arg :list] [join-val :string]) => :string` - `(newline) => :string` + - `(rest-char [arg :string]) => :string` - `(split [arg :string] [split-val :string]) => :list` - `(strip [arg :string]) => :string` @@ -94,6 +96,7 @@ - `(list-reverse [arg :list]) => :int` - `(rest [arg :list]) => :any ; cdr` - `(shuf [arg :list]) => :list ; shuffle the elements of the list` + - `(slice [arg :list] [start-idx :int] [[length :int]]) => :list` - `(zip [arg1 :list] [arg2 :list]) => :list` ### "higher order" diff --git a/interpreter.py b/interpreter.py index dbf8c82..04160cd 100644 --- a/interpreter.py +++ b/interpreter.py @@ -712,3 +712,38 @@ def interpretExists(symbol, args, env): return Literal(Path(file_or_dir.value).resolve().exists()) GLOBALS.register("exists?", Builtin(interpretExists, 1)) + +def interpretFirstChar(symbol, args, env): + ev = evaluate(args[0], env) + if not isinstance(ev, Literal): + raise Exception("'first-char' expects a string") + if len(ev.value) == 0: + raise Exception("string is empty") + return Literal(ev.value[0]) + +GLOBALS.register("first-char", Builtin(interpretFirstChar, 1)) + +def interpretRestChar(symbol, args, env): + ev = evaluate(args[0], env) + if not isinstance(ev, Literal): + raise Exception("'rest-char' expects a string") + return Literal(ev.value[1:]) + +GLOBALS.register("rest-char", Builtin(interpretRestChar, 1)) + +def interpretSlice(symbol, args, env): + lst = evaluate(args[0], env) + if not isinstance(lst, List): + raise Exception("'slice' expects a list as its first argument") + idx = evaluate(args[1], env) + if not isinstance(idx, Literal): + raise Exception("'slice' expects an integer as its second argument") + if len(args) == 2: + return List(lst.args[idx.value - 1:]) + length = evaluate(args[2], env) + if not isinstance(length, Literal): + raise Exception("'slice' expects an integer as its third argument") + diff = idx.value - 1 + length.value + return List(lst.args[idx.value - 1:diff]) + +GLOBALS.register("slice", Builtin(interpretSlice, 2, 3)) |