Case 036

Run-length encoder

run_length_encoder.eml run-length-encodes the DNA-style base sequence "AAAAGGGGCCCCTTTTAAAAGGA" (a genuine RLE use case — simple compression of repeated-symbol sequences, e.g. in bioinformatics or fax-style bitmap rows), producing 4A4G4C4T4A2G1A.

ok: true — round-trip fixpoint reached (python1 == python2)updated 2026-07-19

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EML

eml

# Self-authored for the EML case corpus (no external origin). Run-length
# encodes a sample DNA-style base sequence (a genuine RLE use case in
# bioinformatics) by tracking the current character and its run count in a
# loop, then formatting each run with a tuple + `%`-string-format.

sequence^+"AAAAGGGGCCCCTTTTAAAAGGA"
len(sequence) => length

sequence[0] => current
count^+1
encoded^+""

for i in [1:length-1]:
    sequence[i] => ch
    if ch == current:
        count^+1
    else:
        "%d%s" % (count, current) => piece
        encoded + piece => encoded
        ch => current
        1 => count

"%d%s" % (count, current) => piece
encoded + piece => encoded

"Original: " + sequence => line1
line1^0
"Encoded:  " + encoded => line2
line2^0

Python (deterministic transpilation)

python

sequence = "AAAAGGGGCCCCTTTTAAAAGGA"
length = len(sequence)
current = sequence[0]
count = 1
encoded = ""
for i in range(1, length):
    ch = sequence[i]
    if ch == current:
        count += 1
    else:
        piece = "%d%s" % (count, current)
        encoded = encoded + piece
        current = ch
        count = 1
piece = "%d%s" % (count, current)
encoded = encoded + piece
line1 = "Original: " + sequence
print(line1)
line2 = "Encoded:  " + encoded
print(line2)

stdout (executed)

text

Original: AAAAGGGGCCCCTTTTAAAAGGA
Encoded:  4A4G4C4T4A2G1A

Trace event types

eml:run:starteml:assigneml:augmenteml:outputeml:run:done